ORIGINAL ARTICLE

Duje Lisicic bull Sanja Drakulic bull Anthony Herrel

Domagoj ndashDikic bull Vesna Benkovic bull Zoran Tadic

Effect of competition on habitat utilization in two temperateclimate gecko species

Received 8 July 2011 Accepted 27 December 2011 Published online 24 January 2012 The Ecological Society of Japan 2012

Abstract Competition over spatial niche utilisation isone of most common competitive interactions betweenspecies in sympatry Moreover competitive interactionsmay involve age classes and can fluctuate temporallyConsequently evasive strategies that enable co-existenceare likely to be important in the evolution of speciesassemblages Here we investigate a system of two co-existing species of temperate geckos with similar ecolo-gies (the house geckoHemidactylus turcicus and the wallgecko Tarentola mauritanica) providing an opportunityto study the effect of species interactions Juveniles andadults of both species were investigated throughout theirdaily and annual cycle to explore the effect of inter- andintra-specific interactions on microhabitat use The twospecies showed differences in habitat use for both ageclasses in sympatry In sympatry T mauritanica usesmore open habitats and is more active In contrast Hturcicus is found in more closed habitats closer to theground and to vegetation cover In allopatry H turcicuswas observed in more open habitats closer to theground and to vegetation cover when compared to thepopulation in sympatry with T mauritanica These dif-ferences in habitat usage were significant for both ageclasses Moreover there were differences both insympatry and in allopatry between age classes that weredependent on season In conclusion the presence of acompetitor induces a spatial shift in individuals of bothage classes of H turcicus Observed plasticity in habitatutilisation in both age classes of H turcicus is used toargue for the invasive potential of this species

Keywords Interspecies interaction AElig Lizard ecology AEligNiche shift AElig Spatial niche AElig Species assemblage

Introduction

An animalrsquos niche is a complex ecological phenomenonthat can be subdivided into several dimensions (Pianka1974 Schoener 1974a) Differences in the ecological andphysiological requirements of an individual will deter-mine its position in the different spatial and temporalcomponents of a niche The selection of suitable habi-tats fulfilling requirements for food safety heat andreproduction is of great importance for all organisms(Daly et al 2007) However the co-existence of speciesmay result in an overlap in optimal habitat requirements(ie spatial niche) and represents one of themost commonforms of species interactions (Schoener 1974b) If theoverlap between two interacting species is too great thedemands for similar resources will conflict and may neg-atively affect either both or only one of the two speciesinteracting (Downes and Bauwens 2002 Kumstatovaet al 2004 Merkle et al 2009)

To overcome the potentially negative effects of nichepartitioning many sympatric species evolve strategiesthat allow co-existence in a same area (Vitt and Zani1998 Grbac and Brnin 2006 De Pinho et al 2009) Suchstrategies usually involve niche shifts or character dis-placement that enables niche shifts (Schoener 1975Schoener et al 2005) Evasive strategies have beendocumented in many co-existing ecologically similarspecies of both animals and plants and appear to be ageneral mechanism to avoid competition (Schoener1983 Luiselli 2006) Plasticity in resource use is likely animportant characteristic in the process of co-evolution insympatric populations and enables flexibility in spatialtrophic or temporal niches thus allowing successful co-existence If there is no niche divergence competitiveinteractions may result in lowered body conditionhealth status and fitness of a subdominant species thatmay ultimately lead to its local extinction (Luh and

D Lisicic (amp) AElig S Drakulic AElig D ndashDikic AElig V Benkovic AElig Z TadicDivision of Biology Department of Animal PhysiologyFaculty of Science University of ZagrebRooseveltov trg 6 10 000 Zagreb CroatiaE-mail dujelisicicgmailcomTel +385-1-4877742Fax +385-1-4826260

A HerrelDepartement drsquoEcologie et de Gestion de la BiodiversiteUMR 7179 CNRSMNHN 57 rue CuvierCase postale 55 75231 Paris Cedex 5 France

Ecol Res (2012) 27 551ndash560DOI 101007s11284-011-0921-5

Pimm 1993 Hunt and Bonsall 2009 Dangremond et al2010) As competitive interactions are the result ofecological similarity in requirements these are often themost intensive among individuals of the same species(Pough et al 2001) As such not only heterospecific butalso conspecific niche shifts can occur and may result indifferences in niche utilisation between juvenile andadult individuals (Lima and Moreira 1993 Brischouxet al 2009) or between the sexes (Marquet et al 1990Doughty and Shine 1995 Brecko et al 2008)

Interspecific interactions and niche shift are fre-quently studied using reptiles (usually lizards) as modelspecies (Pianka 1969 Huey and Pianka 1977 Werneret al 2005) and there are many cases where species withsimilar ecological requirements appear to co-exist Forexample Huey and Pianka (Huey and Pianka 1977Pianka and Huey 1978) reported patterns of nicheoverlap and competition between scincid and gekkonidlizards living in the Kalahari Desert and suggested thatdifferences in microhabitat utilisation may be importantin structuring these communities

Two species of nocturnal insectivorous geckos thehouse gecko (Hemidactylus turcicus Linnaeus 1758) andthe moorish gecko (Tarentola mauritanica Linnaeus1758) are often found inhabiting the same areas inMediterranean human-modified habitats (Arnold andOvenden 2002) These geckos share many biologicalcharacteristics which can be expected to result ininterspecific competition However morphological andbehavioural differences between these two species mayallow them to utilise specific temporal and spatial nichesand thus reduce the potentially negative effects ofinterspecific competition (Selcer 1986 Arad et al 1997Johnson et al 2005 Hodar et al 2006) Since H turcicusand T mauritanica have coexisted in Mediterraneanhabitats for a long time it can be assumed that com-petition avoidance strategies exist in the areas of symp-atry However the mechanisms that allow thecoexistence of these two species remain unknown(Capula and Luiselli 1994 Luiselli and Capizzi 1999)

Here we examined the influence of the presence of Tmauritanica on habitat utilisation of H turcicus byexamining populations of H turcicus in sympatry andallopatry on two geographically close and structurallysimilar islands in the Eastern Adriatic Moreover we ex-plored habitat utilisation in different age classes for bothspecies to reveal potential intraspecific niche shifts in thepresence of competition Our aimwas to answer twomainquestions (1) are there any differences in habitat utilisa-tion between sympatric populations ofTmauritanica andH turcicus on the island of Hvar and (2) are there dif-ferences in habitat utilisation between a sympatric popu-lation of H turcicus on the island of Hvar and apopulation ofH turcicus in allopatry on the island of Vis

Insights into the behavioural patterns of both speciesand the selection of a specific well-defined study areaallowed the monitoring of these species throughout theirdiurnal and annual cycle Previous studies on interspe-cies interactions suggest that larger species are usually

better and dominant competitors (Schoener 1975 1983Kjoss and Litvaitis 2001 Merkle et al 2009) Conse-quently we predict that the larger and more aggressiveT mauritanica will induce a habitat shift in the smallerH turcicus in sympatry Previous authors have demon-strated differences between adults and juveniles in nicheutilisation (Downes and Shine 1998 Brischoux et al2009) influences of adults of one species on the juvenilesof another species in sympatry (Museth et al 2010) andcompetition between juveniles of two sympatric species(McGrath and Lewis 2007) led us to predict that habitatuse would be different between juvenile and adult geckosin both species and that these differences are dependenton the presence of a potential competitor

Materials and methods

Study species and site

The house gecko (Hemidactylus turcicus) and the moorishgecko (Tarentola mauritanica) are two typical gekkonidlizards Both species are insectivores mainly nocturnaland associated typicallywith vertical surfaces They live inwarm dry areas and often thrive in modified anthro-pogenic landscapes including olive grows and vineyardsstone walls cliffs rocks ruins and houses Tarentolamauritanica can grow up to 20 cm in total length andemploys a typical sit-and-wait foraging behaviourMoreover it is reported to be territorial and aggressivetowards conspecifics (Carretero 2008) Hemidactylusturcicus is smaller (up to 10 cm in total length) and incontrast to T mauritanica is reported have a more activeforaging style (Capula and Luiselli 1994) Hemidactylusturcicus is more social and can achieve relatively highpopulation densities (Punzo 2001 Locey and Stone 2006)Differences in activity patterns are also noticeable whileH turcicus appears to be an exclusively nocturnal andcrepuscular animal T mauritanica shows significantdiurnal activity in both foraging and thermoregulatorybehaviour (Arnold and Ovenden 2002)

Both species inhabit coastal areas of the Mediterra-nean Sea including the Adriatic coast In the Croatianpart of the Eastern Adriatic H turcicus is widespreadthrough costal areas and on islands while T maurita-nica is present only on the island of Hvar and in thetown of Zadar On both locations species are sympatric(M Loncar 2005 unpublished data) Two islands inEastern Adriatic coast were selected for this study theislands Hvar and Vis Whereas both gecko species arepresent in sympatry on the island of Hvar island of Viscontains only H turcicus The island of Hvar is elon-gated orientated diagonally relative to the mainland andis 68 km long Its area is 29966 km2 and highest pointof the island is 626 m The study area on the island ofHvar is approximately 30 km from the mainland but atthe nearest point the island is only 4 km away from themainland The island of Vis is smaller than the island of

552

Pimm 1993 Hunt and Bonsall 2009 Dangremond et al2010) As competitive interactions are the result ofecological similarity in requirements these are often themost intensive among individuals of the same species(Pough et al 2001) As such not only heterospecific butalso conspecific niche shifts can occur and may result indifferences in niche utilisation between juvenile andadult individuals (Lima and Moreira 1993 Brischouxet al 2009) or between the sexes (Marquet et al 1990Doughty and Shine 1995 Brecko et al 2008)

Interspecific interactions and niche shift are fre-quently studied using reptiles (usually lizards) as modelspecies (Pianka 1969 Huey and Pianka 1977 Werneret al 2005) and there are many cases where species withsimilar ecological requirements appear to co-exist Forexample Huey and Pianka (Huey and Pianka 1977Pianka and Huey 1978) reported patterns of nicheoverlap and competition between scincid and gekkonidlizards living in the Kalahari Desert and suggested thatdifferences in microhabitat utilisation may be importantin structuring these communities

Two species of nocturnal insectivorous geckos thehouse gecko (Hemidactylus turcicus Linnaeus 1758) andthe moorish gecko (Tarentola mauritanica Linnaeus1758) are often found inhabiting the same areas inMediterranean human-modified habitats (Arnold andOvenden 2002) These geckos share many biologicalcharacteristics which can be expected to result ininterspecific competition However morphological andbehavioural differences between these two species mayallow them to utilise specific temporal and spatial nichesand thus reduce the potentially negative effects ofinterspecific competition (Selcer 1986 Arad et al 1997Johnson et al 2005 Hodar et al 2006) Since H turcicusand T mauritanica have coexisted in Mediterraneanhabitats for a long time it can be assumed that com-petition avoidance strategies exist in the areas of symp-atry However the mechanisms that allow thecoexistence of these two species remain unknown(Capula and Luiselli 1994 Luiselli and Capizzi 1999)

Here we examined the influence of the presence of Tmauritanica on habitat utilisation of H turcicus byexamining populations of H turcicus in sympatry andallopatry on two geographically close and structurallysimilar islands in the Eastern Adriatic Moreover we ex-plored habitat utilisation in different age classes for bothspecies to reveal potential intraspecific niche shifts in thepresence of competition Our aimwas to answer twomainquestions (1) are there any differences in habitat utilisa-tion between sympatric populations ofTmauritanica andH turcicus on the island of Hvar and (2) are there dif-ferences in habitat utilisation between a sympatric popu-lation of H turcicus on the island of Hvar and apopulation ofH turcicus in allopatry on the island of Vis

Insights into the behavioural patterns of both speciesand the selection of a specific well-defined study areaallowed the monitoring of these species throughout theirdiurnal and annual cycle Previous studies on interspe-cies interactions suggest that larger species are usually

better and dominant competitors (Schoener 1975 1983Kjoss and Litvaitis 2001 Merkle et al 2009) Conse-quently we predict that the larger and more aggressiveT mauritanica will induce a habitat shift in the smallerH turcicus in sympatry Previous authors have demon-strated differences between adults and juveniles in nicheutilisation (Downes and Shine 1998 Brischoux et al2009) influences of adults of one species on the juvenilesof another species in sympatry (Museth et al 2010) andcompetition between juveniles of two sympatric species(McGrath and Lewis 2007) led us to predict that habitatuse would be different between juvenile and adult geckosin both species and that these differences are dependenton the presence of a potential competitor

Materials and methods

Study species and site

The house gecko (Hemidactylus turcicus) and the moorishgecko (Tarentola mauritanica) are two typical gekkonidlizards Both species are insectivores mainly nocturnaland associated typicallywith vertical surfaces They live inwarm dry areas and often thrive in modified anthro-pogenic landscapes including olive grows and vineyardsstone walls cliffs rocks ruins and houses Tarentolamauritanica can grow up to 20 cm in total length andemploys a typical sit-and-wait foraging behaviourMoreover it is reported to be territorial and aggressivetowards conspecifics (Carretero 2008) Hemidactylusturcicus is smaller (up to 10 cm in total length) and incontrast to T mauritanica is reported have a more activeforaging style (Capula and Luiselli 1994) Hemidactylusturcicus is more social and can achieve relatively highpopulation densities (Punzo 2001 Locey and Stone 2006)Differences in activity patterns are also noticeable whileH turcicus appears to be an exclusively nocturnal andcrepuscular animal T mauritanica shows significantdiurnal activity in both foraging and thermoregulatorybehaviour (Arnold and Ovenden 2002)

Both species inhabit coastal areas of the Mediterra-nean Sea including the Adriatic coast In the Croatianpart of the Eastern Adriatic H turcicus is widespreadthrough costal areas and on islands while T maurita-nica is present only on the island of Hvar and in thetown of Zadar On both locations species are sympatric(M Loncar 2005 unpublished data) Two islands inEastern Adriatic coast were selected for this study theislands Hvar and Vis Whereas both gecko species arepresent in sympatry on the island of Hvar island of Viscontains only H turcicus The island of Hvar is elon-gated orientated diagonally relative to the mainland andis 68 km long Its area is 29966 km2 and highest pointof the island is 626 m The study area on the island ofHvar is approximately 30 km from the mainland but atthe nearest point the island is only 4 km away from themainland The island of Vis is smaller than the island of

552

Hvar with its longest axis being only 17 km and its sur-face area 915 km2 The highest point of the island ofVis is587 m similar to that of Hvar Given the small distancebetween these two islands (plusmn20 km apart) microclimateand vegetation are very similar The climate is typicalMediterranean with long hot summers andmild wintersThe main vegetation type on both islands is macchia withforests composed of typical central Mediterranean plantspecies lentisc and turpentine tree shrubs (Pistacia len-tiscus andP terebinthus) junipers (Juniperus macrocarpaJ phoenicea) strawberry tree (Arbutus undeo) holm oak(Quercus ilex) Aleppo pine (Pinus halepensis) and rockroses (Cistus sp) Both islands have abandoned and activeagricultural areas that include mainly olive growths andvineyards Our study areas on Hvar (4310cent55centcentN1635cent31centcentE) and Vis (4302cent48centcentN 1612cent09centcentE) includesimilar anthropogenic habitats with stone walls fieldcottages water wells and rock piles

Relative population densities of H turcicus (observedgeckos during field surveys and recalculated as numberof geckos per square metre) were greater for the allo-patric population on the island of Vis (013 adultsm2

and 0014 juvenilesm2) compared to those of sympatricpopulation on the island of Hvar (0022 adultsm2 and0009 juvenilesm2) Tarentola mauritanica showed lowerdensities than the sympatric population of H turcicus(0012 adultsm2 and 0001 juvenilesm2) (DL et alunpublished data)

Surveys and habitat sampling

Our study was conducted from April 2002 to December2006 The survey was not constant throughout the yearInstead some months were skipped in a particular yearand surveys for those were made during the followingyear In total three independent data sets from differentyears were collected for each month During monthlysurveys a 24-h period of observation was held on eachisland and search effort was standardised During eachobservation bout transects were walked and suitablehabitats were surveyed for geckos along each transect Onboth islands transects consisted of a variety of differenthabitats used by geckos throughout their annual cycle Toensure that the majority of habitats available and used bygeckos were included in transects preliminary observa-tions were performed in 2002 Transects comprised sev-eral different locations suitable for geckos (field cottagesstonewalls water wells etc) separated by unfavourablehabitat (eg meadow road vineyard) On the island ofHvar a total of 51 survey locations were distributed alonga transect of 32 km and 21 on the island of Vis distrib-uted on a 11 km long transect Each 24-h period ofobservation was divided into four sections morning(70 min before to 2 h after sunrise) daytime evening (2 hbefore to 70 min after sunset) and night The surveylocations were inspected for geckos during each section ofthe day Since morning and evening periods were shorterthan day and night a reduced number of locations were

inspected during those sections However the locationsinspected were constant through all of the surveys and arethus comparable across months and years Geckos werespotted visually using head lamps while inspecting cot-tages waterwells and other hiding places For each geckoobservedwe recorded themonth time of day species age(adult-juveniles) habitat (7 categories) microhabitat (24categories) substrate (9 categories) type of behaviour (6categories) cardinal direction (5 categories) position(inside or outside of shelter place 3 categories) heightfrom the ground the distance frominside a shelter thedistance frominside vegetation and the inclination (seeAppendix) All habitat categories were present on bothislands Age classes were distinguished visually by sizeGeckoswere classified as juveniles if theywere too small tobe sexually active (H turcicus pound 4 cm T mauritanicapound 55 cm DL personal observation Atzori et al 2007)There is some error associated with the visual identifica-tion of age classes which was however reduced by theprior experience of the observer and the fact that visualestimation was performed by the same observer over thecourse of study

We grouped our data into four seasons winter(December January and February) spring (MarchApril and May) summer (June July and August) andautumn (September October and November) Time ofday was grouped into four distinct categories morningday evening and night

Statistical analysis

We analysed two different data sets (1) data for T mau-ritanica andH turcicus in sympatry onHvar and (2) datafrom populations ofH turcicus onHvar and Vis Prior toanalysis continuous data were log10-transformed Toreduce the dimensionality of our data set we performedfactor analyses with varimax rotation on all measuredmicrohabitat characteristics (ie habitat microhabitatsubstrate type of behavior cardinal direction positionheight from the ground the distance frominside a shelterthe distance frominside vegetation and the inclination)Extracted factor scores with eigenvalues greater than onewere saved and used in a MANCOVA with island (Hvarvs Vis) species (H turcicus vs T mauritanica) and ageclass (adult vs juvenile) as fixed factors and season andtime of day as covariates Prior to analysis factor scoreswere checked for assumptions of normality and homo-scedascity The level of significance used in the analysiswas set at 005 All non-significant interactions were re-moved from the final model All analyses were performedusing SPSS v 170 (SPSS Chicago IL)

Results

In total data on habitat preference for 6197 geckoswere collected over the 4-year period of study More

553

detailed information about the number of geckos ob-served and some general habitat preferences are given inTable 1

A factor analysis performed on micro-habitat dataduring the 24-h cycle through all seasons for both spe-cies of geckos (sympatry) on the island of Hvar retainedthree factors that jointly explained 6134 of the vari-ation in the data (Table 2 Fig 1) Type of behavior wasstrongly positively orientated and in-out and micro-habitat were strongly negatively correlated with the firstfactor The second factor showed strong and positivecorrelations with height and distance to vegetation Thethird factor was strongly and positively correlated withhabitat and substrate

A MANCOVA performed on the micro-habitat datafor both species of geckos on the island of Hvar duringa 24-h cycle for all seasons indicated significant dif-ferences between species and age classes as well as a

significant seasonal (co-variate) effect The two-wayinteraction between species and age class was also sig-nificant (Table 3)

Subsequent univariate ANCOVArsquos indicated significantdifferences between species on factors one (F12314 =11028 P lt 0001) two (F12314 = 677 P = 0009) andthree (F12314 = 58933 P lt 0001) (Fig 2a) Indeed Tmauritanica is found frequently outside hiding places andmore often uses open habitats and microhabitats Also itcan be found at greater heights as well as farther from thevegetation cover Furthermore it performs behavioursassociated with high scores in our analysis like activity andbasking more frequently It uses substrates that are conve-nient for warming and basking like wooden debris bark orplasticmore often In contrastH turcicus is found in closerproximity to the groundandnear or under vegetation coverMoreover it preferentially uses closed habitats like waterwells andfield cottagesDifferencesbetweenage classesweresignificant on factor one only (F12314 = 538 P = 002)This implies that juveniles of both species are more activeandperformthermoregulatorybehaviours (likebaskingandindirect warming) more often compared to adults Juvenilesof both species use openmicrohabitats more frequently andventure away from hiding places and vegetation cover Theseasonal effect was significant on factors one (F12314 =861 P lt 0001) and two (F12314 = 4913 P lt 0001)Season had a significant effect on the type of behaviourmicrohabitat selection and distance to hiding place andvegetation cover in both species Interaction effects ofspecies and age class were significant on factors two(F12314 = 782 P = 0005) and three (F12314 = 474P = 003) indicating that the habitat use of age classeswasnot identical for both species

A factor analysis performed on micro-habitat dataduring the 24-h cycle through all seasons comparingsympatric (Hvar) and allopatric (Vis) populations of Hturcicus retained three factors that jointly explained

Table 1 Number of geckos observed on the islands of Hvar and Vis classified by species age year and seasonTM Tarentola mauritanicaHT Hemidactilus turcicus Ad adults Juv Juveniles

Island Species Season Year All years Positiona

2003 2004 2005 2006 Inside 0ut

Ad Juv Ad Juv Ad Juv Ad Juv Ad Juv Ad Juv Ad Juv

Hvar TM Spring 100 11 96 27 89 28 19 10 304 76 187 33 117 43Summer 180 23 32 12 150 14 71 9 433 58 161 25 272 33Autumn 64 49 0 0 61 54 51 40 176 143 106 68 70 75Winter 36 17 26 11 79 25 29 22 170 75 150 52 20 23

HT Spring 105 22 139 28 113 32 22 15 379 97 312 83 67 14Summer 73 11 34 9 107 21 64 23 278 64 156 21 122 43Autumn 80 27 0 0 134 88 58 58 272 173 250 134 22 39Winter 27 1 40 3 74 31 64 55 205 90 199 82 6 8

Vis HT Spring 260 31 463 30 235 13 40 1 998 75 886 46 112 29Summer 133 19 61 19 98 7 52 5 344 50 99 8 245 42Autumn 300 45 0 0 305 60 93 42 698 147 603 100 95 47Winter 111 8 265 7 205 24 220 52 801 91 801 89 0 2

Total 6197

aThe position of the geckos relative to hiding places is also presented

Table 2 Factor loadings resulting from a factor analysis withvarimax rotation on habitat data of geckos observed during a 24-hcycle throughout all seasons for two species of geckos (H turcicusand T mauritanica) found in sympatry

Factor

1 2 3

Eigenvalue 33 162 123 of variance explained 3289 1619 1226Habitat 0283 0057 0761a

In-out 0877a 0178 0076Microhabitat 0736a 0230 0284Substrate 0104 0101 0799a

Activity 0721a 0063 0000Orientation 0007 0216 0257Height 0121 0870a 0184Log (inside-outside) (lower is inside) 0656 0261 0102Log (dist to veg) (lower is under veg) 0387 0803a 0119Log (inclination) 0563 0240 0443aIndicate factor loadings greater than 07

554

6752 of the variation in the data (Table 4) In-outmicrohabitat height and distance to vegetation werestrongly positively correlated while distance to hidingplace was strongly negatively correlated with the firstfactor Substrate was strongly positively correlated withsecond factor and inclination was strongly positivelycorrelated with the third factor

A MANCOVA performed on the factor scores onmicrohabitat data for allopatric and sympatric popula-tions of H turcicus indicated significant differences be-tween populations on different islands and age classeswith significant seasonal (co-variate) and time of day(co-variate) effects The two-way interaction betweenislands and age classes was also significant (Table 3)

Subsequent univariate ANCOVArsquos indicated signifi-cant differences between populations inhabiting differentislands on factors one (F13237 = 2426 P lt 0001) two(F13237 = 11315 P lt 0001) and three (F13237 =2476 P lt 0001) (Fig 2b) The individuals from thepopulation inhabiting the island ofHvar weremore often

associated with closed microhabitats were more oftenfound inside the shelters at greater heights and furtheraway from vegetation cover Individuals of the popu-lation from the island of Hvar were found on sub-strates like metal wood or plastic more often andwere more orientated toward western and southernexposures Age class differences were significant onfactors one (F13237 = 869 P = 0003) and two

Fig 1 Scatter plot illustrating the results of a factor analysisperformed on the microhabitat data for two species of geckos(Hemidactilus turcicus and Tarentola mauritanica) occurring insympatry on the island of Hvar

Table 3 Results of MANCOVA performed on micro-habitat dataduring a 24-h cycle for all seasons The level of significance used inanalysis was 005

Effect Wilksrsquo lambda df F P

MANCOVA on micro-habitat data for two species of geckos onthe island of HvarSpecies 075 3 2312 26171 lt0001Age classes 099 3 2312 415 0006Season (co-variate) 094 3 2312 4537 lt0001Species middot age classes 099 3 2312 408 0007MANCOVA on the factor scores on microhabitat data forallopatric and sympatric population of H turcicusIsland 095 3 3235 5398 lt0001Age classes 097 3 3235 2769 lt0001Season (co-variate) 087 3 3235 15554 lt0001Time of day (co-variate) 095 3 3235 5816 lt0001Species middot age classes 098 3 3235 2097 lt0001

Fig 2 Factor loadings values (y axis) resulting from factoranalyses with varimax rotation on microhabitat characteristicsillustrating differences in microhabitat utilisation a Graph illus-trating differences in microhabitat use between H turcicus and Tmauritanica on the island of Hvar b Graph illustrating differencesin microhabitat use between H turcicus occurring in sympatry withT mauritanica on island of Hvar versus in allopatry on island ofVis c Graph illustrating differences in habitat use of H turcicus ofdifferent age classes in sympatry and allopatry

555

(F13237 = 6766 P lt 0001) (Fig 2c) Adults on bothislands were found more often in closed microhabitatsinside hiding places at greater heights and at greaterdistance from vegetation However juveniles on bothislands chose substrates like metal wood plastic orother types of man-made debris more often Theseasonal effect was significant on factors one(F13237 = 2668 P lt 0001) two (F13237 = 9077P lt 0001) and three (F13237 = 6524 P lt 0001) Inaddition time of day was significant on factors one(F13237 = 16177 P lt 0001) and three (F13237 =859 P = 0003) This implies that both seasonalchanges and daytime cycle have a significant effect onmicrohabitat utilisation distance to hiding place andvegetation cover and the choice of height substrateand cardinal direction The two-way interactionbetween island and age class was significant on factorsone (F13237 = 2099 P lt 0001) two (F13237 =2364 P lt 0001) and three (F13237 = 1916 P lt0001) indicating that the age classes used differentmicrohabitats on the two islands

Discussion

A previous study on relative population densities com-paring T mauritanica and H turcicus indicated lowerpopulation densities of H turcicus in sympatry (Hvar)as compared to the populations in allopatry (Vis)Moreover populations in syntopy showed lower popu-lation densities than population in allotopy on the sameisland (Hvar) and allotopic populations on Hvarshowed lower densities than allopatric populations onVis indicating a strong effect of the presence of Tmauritanica on H turcicus (DL et al unpublisheddata) The results of the present study reveal differencesin habitat and microhabitat use of these same two gecko

species in sympatry Moreover differences in habitat usecan be demonstrated between populations of H turcicusin allopatry (Vis) versus those on Hvar in sympatry withT mauritanica (Fig 2)

Species differences in sympatry

Our results suggest differentiation in habitat use amongthese two species in sympatry (Table 3 Fig 2a) Differ-ences in microhabitat use in ecologically similar species insympatry are common (Reinert 1984 Kumstatova et al2004 Daly et al 2007 Yamauchi and Miki 2009 Chilloet al 2010) Although spatial segregation is often sug-gested as one of the mechanisms allowing the coexistencebetweendifferent species (Schoener 1974a b) it is unlikelythat sympatric species are completely spatially isolatedand in many cases some degree of spatial overlap doesoccur (Schoener 1983) Thus even if our data suggestsegregation on a small spatial scale between T maurita-nica and H turcicus in sympatry it is unlikely that com-petition does not occur at all More likely the reportedmicrohabitat differences function to decrease the com-petitive interactions between T mauritanica and H tur-cicus Moreover the observed differences in habitat usagemay stem from the species-specific biological require-ments as suggested previously (Gill et al 1994a b Punzo2001 Hitchcock and McBrayer 2006) Consequently theecological differences between these species may allowtheir coexistence in communal habitats A spatial nicheshift like that reported here has been observed previouslyin other sympatric associations of ecologically similarspecies (Schoener 1975 Pianka and Huey 1978 Grbacand Brnin 2006) Our data are similar to that reported forhabitat use in the tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric versus allopatric localities(Kumstatova et al 2004) These two related passerinesshow differences in habitat use in allopatry and expressniche shifts when occurring in sympatry similar to whatwe observed in our two studied geckos

Allopatric versus sympatric populations of H turcicus

Habitat divergence between allopatric and sympatricpopulations of H turcicus may originate from thepresence or absence of the potential competitor Tmauritanica (Table 3 Fig 2b) Previous studies on Tmauritanica and H turcicus in sympatry suggested sim-ilarity in niche occupation between species (Capula andLuiselli 1994 Luiselli and Capizzi 1999) Moreover ourdata on relative population densities suggests competi-tive interactions between T mauritanica and H turcicus(DL et al unpublished data) Although the habitatanalysis presented here suggests differences in spatialniche in sympatry to test whether the presence of apotential competitor affects habitat use one must com-pare populations in different competitive scenarios(sympatry vs allopatry) Our data show that H turcicus

Table 4 Factor loadings resulting from a factor analysis withvarimax rotation performed on the habitat data of geckos observedduring the 24-h cycle through all seasons for sympatric (Hvar) andallopatric (Vis) populations of H turcicus

Factor

1 2 3

Eigenvalue 4333 14 1018 of variance explained 4333 1400 1018Habitat 0087 0550 0011In-out 0903a 0131 0172Microhabitat 0861a 0244 0065Substrate 0089 0786a 0255Activity 0678 0379 0230Orientation 0280 0673 0073Height 0735a 0119 0439Log (inside-outside) (lower is inside) 0754a 0152 0306Log (dist to veg) (lower is under veg) 0766a 0285 0114Log (inclination plus) 0148 0134 0858a

aFactor loadings greater than 07

556

in allopatry uses all types of microhabitats needed tofulfil its ecological demands In sympatry H turcicuscan be observed more in closed habitats like water wellsand field cottages the types of habitat that are usuallyavoided by the heliophilous and more active T mauri-tanica Changes in spatial niche in allopatry as comparedto sympatry like that observed in this study have beenreported for a wide variety of taxa including insects(Honkavaara et al 2011) amphibians (Rice et al 2009)and birds (Kirschel et al 2009) and suggests that thismay be a general phenomenon However the observedhabitat difference in sympatric versus allopatric popu-lations of H turcicus may potentially be related to dif-ferences in available microhabitats between the twoislands Indeed islands show slight differences in fieldcottage and stonewall constructions As these differencesare generally minor and do not reflect the observeddifferences in habitat use it is likely that observed dif-ferences in spatial niche are driven by the presence ofcompetition between two ecologically similar specieswith T mauritanica being dominant over H turcicus

Intraspecific differences in habitat use

Interestingly in both species independent of the pres-ence of a potential competitor we observed differenthabitat use between age classes (Table 3) Juvenilegeckos more often used open habitats and venture intomicrohabitats rarely occupied by adults Other studieshave similarly demonstrated that juveniles differ inspatial niche from adult conspecifics (Blouin-Demerset al 2007) One of the arguments put forward to explainthis difference is the avoidance of predation by adults onjuveniles (Pough et al 2001) Alternatively avoidance ofcompetition with adults (Brischoux et al 2009) popu-lation dispersion strategies (Punzo 2001) or lack ofexperience in young animals have been suggested asexplanations for this pattern (Pough et al 2001) One ofthe most studied European lizard species Lacerta agilisshows similar ontogenic shifts in microhabitat usageYoung individuals typically use open habitats likemeadows while adults are usually found in vicinity ofbushes that can be used as shelters These differences inhabitat use suggest behavioural interactions betweenadults and juveniles Meadows do not provide enoughshelter for adult lizards and thick grass may disturb theirlocomotion while juveniles avoid habitats occupied byadults and find enough cover in meadows (Amat et al2003 Nemes et al 2006) The results of our study sug-gest that such behavioural strategies may also be em-ployed in the gecko species studied here Our results alsoindicate that the difference in microhabitat use betweenage classes in sympatry is species specific implying thatwhen occurring in the same habitat the two age classesof each species each have their unique requirementsresulting in a decrease in intra- but also interspeciescompetitive interactions In addition age class-relateddifferences in habitat use detected in H turcicus are

island specific This result implies a spatial niche shiftbetween age classes in H turcicus in the absence of thecompetitively superior T mauritanica

Interestingly not only is the habitat use in both ageclasses of H turcicus affected by the presence of T mau-ritanica but both age classes also show a shift in habitatuse in allopatry compared to sympatry (Fig 2c) Nichewidening in the absence of competition is a well-docu-mented phenomenon (Rice et al 2009) The habitat shiftobserved in this study illustrates how profound is theinfluence of the presence of the competitively superior Tmauritanica onH turcicus In many species the presenceof a sympatric heterospecific influences only one age classFor example a study on the interactions between twosimilar trout species implied negative competitive inter-actions in juveniles but not adults (McGrath and Lewis2007) Yet other studies indicate competitive interactionsoccurring principally between adults (Torok and Toth1999) In some cases interspecific age class-related inter-actions were reported with adults of one species influ-encing juveniles of the other species (Museth et al 2010)

The ability of H turcicus to adapt its habitatrequirements in both age classes may be an explanationfor its invasive potential This species is known to haveinvaded distant areas that are far outside its naturalgeographic area mostly by means of human-based dis-persal (Selcer 1986 Locey and Stone 2006) Our studyon spatial niche shifts suggests a potential origin of theecological plasticity allowing H turcicus to adapt to thenew environment Since in its native geographic rangeH turcicus often enters into competition with T mau-ritanica it would seem beneficial for H turcicus to retainsome level of plasticity that allows coexistence with acompetitively stronger heterospecifics Moreover ourresults suggest that this plasticity is characteristic of bothadults and juveniles

Effect of covariates (season and time of day)

Finally our results also indicate a significant seasonaleffect on the spatial niche utilisation between species insympatry as well as among populations of H turcicus insympatry versus allopatry Such a temporally fluctuatingutilisation of the available habitat has been reported formany different taxa (Pianka 1969 Ricklefs et al 1981Pough et al 2001) and may further impose demands onflexibility in habitat use

However it is important to point out the lack of asignificant effect of the time of the day in the sympatricpopulation on Hvar This implies that both species havesimilar behavioural patterns during the course of theday Nevertheless both species exhibit similar oscilla-tions in habitat utilisation showing greater movementsduring the night hours and staying near hiding placesduring daytime In addition both species demonstratepositive thermoregulatory behaviour during daytimehours but with different thermoregulatory strategies(direct sunlight basking vs convective heating) Inter-

557

estingly our results indicate difference in habitat util-isation between sympatric versus allopatric populationsof H turcicus This implies that two populations differnot only in the seasonal characteristics of habitat pref-erences but also in a way of habitat utilisation on a dailybasis Such differences could be the result of differentclimate and ecological characteristics between islandsbut are likely affected by the presence of another geckospecies on the island of Hvar

In summary the data presented here indicate habitatsegregation in sympatry as well as release of competitiverestraints in allopatry in the subordinate species Giventhe often complicated mechanisms of interspecies inter-actions and species co-existence (Ricklefs et al 1981Pough et al 2001 Merkle et al 2009) our data may addto a better understanding of these processes Whereasour data suggest effects of competition on habitat use in

H turcicus further studies including other componentsof the ecological niche such as diet and temperature areneeded to better understand the ecological strategies ofthis species that allow it to coexist with T mauritanica

Acknowledgements We thank all the people that participated in thefield work Many thanks to the families of Petar Zitko and TonciMaroevic for accommodation on the islands of Vis and HvarMany thanks to Pava and Simun Lisicic for their continued sup-port during the study This work was supported through grant No119-0000000-1285 of the Ministry of Science Education and Sportof the Republic of Croatia to ZT

Appendix

(See Table 5)

Table 5 Categories and subcategories of habitat used in measuring habitat utilisation forH turcicus and T mauritanica on island of Hvar(populations in sympatry) and island of Vis (H turcicus population in allopatry)

Category of habitat Sub-categoryof habitat

Description

Habitat General habitat typesWater wellField cottageField doors Specific constructions that include wooden doors two columns

and small roof above doors Intensively used by geckosWall All types of walls and stonewallsTreeColumn Power columns or field marks of column formNear to ground habitat Ground grass piles of rocks or twigs man-made debris

Position Outside Position inside or outside of shelter placeAt the entranceInside

Microhabitat Various types of microhabitat used by geckosOpen habitats Habitats that were open or offer minimal protection from

weather conditions and predatorsGroundLogStoneWallUnder stoneboardInside hole Shallow holes at open habitatsNear ceilingCeiling

Closed habitats Inside closed habitats that offers protection fromenvironmental conditions ie inside field cottage

WallBoardGroundUnder stoneboardInside holeIn crevice Crevices are defined as all types of holes deep enough that

geckos can hide from weather conditions and predatorsAnthropogenic debris Old clothes piles of twigs glasses old boxes with toolsNear ceilingceiling

Inside water well entrance Water well entrances usually used as warming spotsWallUnder panelPanel

Inside water well Very stable conditions ideal hiding places from weatherconditions

WallNear ceilingInside holeCeiling

558

References

Amat F Llorente GA Carretero MA (2003) A preliminary studyon thermal ecology activity times and microhabitat use ofLacerta agilis (Squamata Lacertidae) in the Pyrenees FoliaZool 52413ndash422

Arad Z Schwarzbaum A Werner Y (1997) Temperature selectionand thermoregulation in the Moorish gecko Tarentola mauri-tanica Amphibia Reptilia 69269ndash282

Arnold EN Ovenden D (2002) A field guide to the reptiles andamphibians of Britain and Europe 2nd edn Harper CollinsLondon

Atzori A Berti F Cencetti T Fornasiero S Tamburini M ZuffiMAL (2007) Advances in methodologies of sexing and markingless dimorphic gekkonid lizards the study case of the Moorishgecko Tarentola mauritanica Amphibia Reptilia 28449ndash454

Blouin-Demers G Bjorgan LPG Weatherhead PJ (2007) Changesin habitat use and movement patterns with body size in blackratsnakes (Elaphe obsoleta) Herpetologica 63421ndash429

Brecko J Huyghe K Vanhooydonck B Herrel A Grbac I VanDamme R (2008) Functional and ecological relevance ofintraspecific variation in body size and shape in a lizard Po-darcis melisellensis Biol J Linn Soc 94251ndash264

Brischoux F Bonnet X Shine R (2009) Determinants of dietaryspecialization a comparison of two sympatric species of seasnakes Oikos 118145ndash151

Capula M Luiselli L (1994) Tropic niche overlap in sympatricTarentola mauritanica and Hemidactylus turcicus a preliminarystudy Herpetol J 424ndash25

Carretero MA (2008) Preferred temperatures of Tarentola mauri-tanica in spring Acta Herpetol 357ndash64

Chillo V Rodrıguez D Ojeda AR (2010) Niche partitioning andcoexistence between two mammalian herbivores in the drychaco of Argentina Acta Oecol 36611ndash616

Daly BD Dickman CR Crowther MS (2007) Selection of habitatcomponents by two species of agamid lizards in sandridgedesert central Australia Austral Ecol 32825ndash833

Dangremond EM Pardini EA Knight TM (2010) Apparentcompetition with an invasive plant hastens the extinction of anendangered lupine Ecology 912261ndash2271

De PinhoWF Colli GR Vitt LJ (2009) Determinants of assemblagestructure in Neotropical dry forest lizards Aust Ecol 3497ndash115

Doughty P Shine R (1995) Life in two dimensions natural historyof the southern leaf-tailed gecko Phyllurus platurus Herpeto-logica 51193ndash201

Downes S Bauwens D (2002) An experimental demonstration ofdirect behavioural interference in two Mediterranean lacertidlizard species Anim Behav 631037ndash1046

Downes S Shine R (1998) Heat safety or solitude Using habitatselection experiments to identify a lizardrsquos priorities AnimBehav 551387ndash1396

Gill MJ Guerrero F Perez-Mellado V (1994a) Diel variation inpreferred body temperatures of the Moorish gecko Tarentolamauritanica during summer Herpetol J 456ndash59

Gill MJ Guerrero F Perez-Mellado V (1994b) Seasonal variationin diet composition and prey selection in the mediterraneangecko Tarentola mauritanica Isr J Zool 4061ndash74

Grbac I Brnin K (2006) Habitat use of sympatric populations ofPodarcis sicula and P melisellensis on a small Adriatic islandPeriod Biol 108177ndash182

Hitchcock MA McBrayer LD (2006) Thermoregulation in noc-turnal ectotherms seasonal and intraspecific variation in theMediterranean Gecko (Hemidactylus turcicus) J Herpetol40185ndash195

Hodar JA Pleguezuelos JM Villafranca C Frenandes-CardeneteJR (2006) Foraging mode of the Moorish gecko Tarentolamauritanica in an arid environment inferences from abioticsetting prey availability and dietary composition J AridEnviron 6583ndash93

Table 5 continued

Category of habitat Sub-categoryof habitat

Description

SubstrateOld clothPaperConcreteStone-concreteStoneWoodBrickPlastic glassMetalTileDirt grass

Type of behaviorStillStillactive Geckos found standing still outside the typical hiding places

ie on wall inside field cottage during cold dayActiveEatingWarmingStillwarming Inactive non-moving geckos that chose warming positions ie

inside water well entrance during winter monthsSun bathing

Cardinal directionNone Geckos found in the middle of field cottage or water well had

no general cardinal directionNorthEastWestSouth

559

Honkavaara J Dunn DW Ilvonen S Suhonen J (2011) Sympatricshift in a male sexual ornament in the damselfly Calopteryxsplendens J Evol Biol 24139ndash145 doi101111j1420-9101201002146x

Huey RB Pianka ER (1977) Patterns of niche overlap amongbroadly sympatric versus narrowly sympatric Kalahari lizards(Scincidae Mabuya) Ecology 5819ndash28

Hunt JFG Bonsall MB (2009) The effects of colonization extinc-tion and competition on co-existence in metacommunitiesJ Anim Ecol 78866ndash879

Johnson J McBrayer LD Saenz D (2005) Allometry sexual sizedimorphism and niche partitioning in the Mediterranean gecko(Hemidactylus turcicus) Southwest Nat 50435ndash439 doi1018940038-4909(2005)050[0435ASSDAN]20CO2

Kirschel ANG Blumstein DT Smith TB (2009) Character dis-placement of song and morphology in African tinkerbirds ProcNatl Acad Sci USA 1068256ndash8261

Kjoss V Litvaitis J (2001) Community structure of snakes in ahuman-dominated landscape Biol Conserv 98285ndash292

Kumstatova T Brinke T Tomkova S Fuchs R Petrusek A (2004)Habitat preferences of tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric and allopatric localitiesJ Ornithol 145334ndash342 doi101007s10336-004-0048-3

Lima A Moreira G (1993) Effects of prey size and foraging modeon the ontogenetic change in feeding niche of Colostethusstephani (Anura Dendrobatidae) Oecologia 9593ndash120

Locey KJ Stone PA (2006) Factors affecting range expansion inthe introduced Mediterranean gecko Hemidactylus turcicusJ Herpetol 40526ndash530

Luh HK Pimm SL (1993) The assembly of ecological communitiesa minimalist approach J Anim Ecol 62749ndash765

Luiselli L (2006) Resource partitioning and interspecific competi-tion in snakes the search for general geographical and guildpatterns Oikos 114193ndash211

Luiselli L Capizzi D (1999) Ecological distribution of the geckosTarentola mauritanica and Hemidactylus turcicus in the urbanarea of Rome in relation to age of buildings and condition ofthe walls J Herpetol 33316ndash319

Marquet PA Bozinovic F Medel RG Werner YL Jaksic FM(1990) Ecology of Garthia gaudichaudi a gecko endemic to thesemiarid region of Chile J Herpetol 24431ndash434

McGrath CC Lewis WM Jr (2007) Competition and predation asmechanisms for displacement of Greenback Cutthroat Trout byBrook Trout Trans Am Fish Soc 1361381ndash1392

Merkle JA Stahler DR Smith DW (2009) Interference competitionbetween gray wolves and coyotes in Yellowstone NationalPark Can J Zool 8756ndash63

Museth J Borgstroslashm R Brittain JE (2010) Diet overlap betweenintroduced European minnow (Phoxinus phoxinus) and youngbrown trout (Salmo trutta) in the lake Oslashvre Heimdalsvatn aresult of abundantresources or forced niche overlap Hydrobi-ologia 64293ndash100 doi101007s10750-010-0162-6

Nemes S Vogrin M Hartel T Ollerer K (2006) Habitat selection atthe sand lizard (Lacerta agilis) ontogenetic shifts N West JZool 217ndash26

Pianka ER (1969) Sympatry of desert lizards (Ctenotus) in WesternAustralia Ecology 501012ndash1030

Pianka ER (1974) Niche overlap and diffuse competition ProcNatl Acad Sci USA 712141ndash2145

Pianka ER Huey RB (1978) Comparative ecology resource util-isation and niche segregation among gekkonid lizards in theSouthern Kalahari Copeia 4691ndash701

Pough FH Andrews RM Cadle JE Crump ML Savitzky AHWells KD (2001) Herpetology 2nd edn Prentice-Hall Engle-wood Cliffs NJ

Punzo F (2001) The Mediterranean gecko Hemidactylus turcicuslife in an urban landscape Fla Sci 6456ndash66

Reinert HK (1984) Habitat variation within sympatric snakepopulations Ecology 651673ndash1682

Rice AM Leichty AR Pfennig DW (2009) Parallel evolution andecological selection replicated character displacement inspadefoot toads Proc R Soc B 2764189ndash4196 doi101098rspb20091337

Ricklefs RE Cochran D Pianka ER (1981) A morphologicalanalysis of the structure of communities of lizards in deserthabitats Ecology 621474ndash1483

Schoener TW (1974a) The compression hypothesis and temporalresource partitioning Proc Natl Acad Sci USA 714169ndash4172

Schoener TW (1974b) Resource partitioning in ecological com-munities Science 18527ndash39

Schoener TW (1975) Presence and absence of habitat shift in somewidespread lizard species Ecol Monogr 45233ndash258

Schoener TW (1983) Field experiments on interspecific competi-tion Am Nat 122240ndash285

Schoener TW Losos JB Spiller DA (2005) Island biogeography ofpopulations an introduced species transform survival patternsScience 3101807ndash1809 doi101126science1120165

Selcer KW (1986) Life history of a successful colonizer the Med-iterranean gecko Hemidactylus turcicus in Southern TexasCopeia 4956ndash962

Torok J Toth L (1999) Asymmetric competition between two titspecies a reciprocial removal experiment J Anim Ecol68338ndash345

Vitt LJ Zani PA (1998) Prey use among sympatric lizard species inlowland rain forest of Nicaragua J Trop Ecol 14537ndash559

Werner YL Takahashi H Mautz WJ Ota H (2005) Behavior ofthe terrestrial nocturnal lizards Goniurosaurus kuroiwae ku-roiwae and Eublepharis macularius (Reptilia Eublepharidae) ina thigmothermal gradient J Ther Biol 30247ndash254 doi101016jjtherbio200412004

Yamauchi A Miki T (2009) Intraspecific niche flexibility facilitatesspecies coexistence in a competitive community with a fluctu-ating environment Oikos 11855ndash66

560

detailed information about the number of geckos ob-served and some general habitat preferences are given inTable 1

A factor analysis performed on micro-habitat dataduring the 24-h cycle through all seasons for both spe-cies of geckos (sympatry) on the island of Hvar retainedthree factors that jointly explained 6134 of the vari-ation in the data (Table 2 Fig 1) Type of behavior wasstrongly positively orientated and in-out and micro-habitat were strongly negatively correlated with the firstfactor The second factor showed strong and positivecorrelations with height and distance to vegetation Thethird factor was strongly and positively correlated withhabitat and substrate

A MANCOVA performed on the micro-habitat datafor both species of geckos on the island of Hvar duringa 24-h cycle for all seasons indicated significant dif-ferences between species and age classes as well as a

significant seasonal (co-variate) effect The two-wayinteraction between species and age class was also sig-nificant (Table 3)

Subsequent univariate ANCOVArsquos indicated significantdifferences between species on factors one (F12314 =11028 P lt 0001) two (F12314 = 677 P = 0009) andthree (F12314 = 58933 P lt 0001) (Fig 2a) Indeed Tmauritanica is found frequently outside hiding places andmore often uses open habitats and microhabitats Also itcan be found at greater heights as well as farther from thevegetation cover Furthermore it performs behavioursassociated with high scores in our analysis like activity andbasking more frequently It uses substrates that are conve-nient for warming and basking like wooden debris bark orplasticmore often In contrastH turcicus is found in closerproximity to the groundandnear or under vegetation coverMoreover it preferentially uses closed habitats like waterwells andfield cottagesDifferencesbetweenage classesweresignificant on factor one only (F12314 = 538 P = 002)This implies that juveniles of both species are more activeandperformthermoregulatorybehaviours (likebaskingandindirect warming) more often compared to adults Juvenilesof both species use openmicrohabitats more frequently andventure away from hiding places and vegetation cover Theseasonal effect was significant on factors one (F12314 =861 P lt 0001) and two (F12314 = 4913 P lt 0001)Season had a significant effect on the type of behaviourmicrohabitat selection and distance to hiding place andvegetation cover in both species Interaction effects ofspecies and age class were significant on factors two(F12314 = 782 P = 0005) and three (F12314 = 474P = 003) indicating that the habitat use of age classeswasnot identical for both species

A factor analysis performed on micro-habitat dataduring the 24-h cycle through all seasons comparingsympatric (Hvar) and allopatric (Vis) populations of Hturcicus retained three factors that jointly explained

Table 1 Number of geckos observed on the islands of Hvar and Vis classified by species age year and seasonTM Tarentola mauritanicaHT Hemidactilus turcicus Ad adults Juv Juveniles

Island Species Season Year All years Positiona

2003 2004 2005 2006 Inside 0ut

Ad Juv Ad Juv Ad Juv Ad Juv Ad Juv Ad Juv Ad Juv

Hvar TM Spring 100 11 96 27 89 28 19 10 304 76 187 33 117 43Summer 180 23 32 12 150 14 71 9 433 58 161 25 272 33Autumn 64 49 0 0 61 54 51 40 176 143 106 68 70 75Winter 36 17 26 11 79 25 29 22 170 75 150 52 20 23

HT Spring 105 22 139 28 113 32 22 15 379 97 312 83 67 14Summer 73 11 34 9 107 21 64 23 278 64 156 21 122 43Autumn 80 27 0 0 134 88 58 58 272 173 250 134 22 39Winter 27 1 40 3 74 31 64 55 205 90 199 82 6 8

Vis HT Spring 260 31 463 30 235 13 40 1 998 75 886 46 112 29Summer 133 19 61 19 98 7 52 5 344 50 99 8 245 42Autumn 300 45 0 0 305 60 93 42 698 147 603 100 95 47Winter 111 8 265 7 205 24 220 52 801 91 801 89 0 2

Total 6197

aThe position of the geckos relative to hiding places is also presented

Table 2 Factor loadings resulting from a factor analysis withvarimax rotation on habitat data of geckos observed during a 24-hcycle throughout all seasons for two species of geckos (H turcicusand T mauritanica) found in sympatry

Factor

1 2 3

Eigenvalue 33 162 123 of variance explained 3289 1619 1226Habitat 0283 0057 0761a

In-out 0877a 0178 0076Microhabitat 0736a 0230 0284Substrate 0104 0101 0799a

Activity 0721a 0063 0000Orientation 0007 0216 0257Height 0121 0870a 0184Log (inside-outside) (lower is inside) 0656 0261 0102Log (dist to veg) (lower is under veg) 0387 0803a 0119Log (inclination) 0563 0240 0443aIndicate factor loadings greater than 07

554

6752 of the variation in the data (Table 4) In-outmicrohabitat height and distance to vegetation werestrongly positively correlated while distance to hidingplace was strongly negatively correlated with the firstfactor Substrate was strongly positively correlated withsecond factor and inclination was strongly positivelycorrelated with the third factor

A MANCOVA performed on the factor scores onmicrohabitat data for allopatric and sympatric popula-tions of H turcicus indicated significant differences be-tween populations on different islands and age classeswith significant seasonal (co-variate) and time of day(co-variate) effects The two-way interaction betweenislands and age classes was also significant (Table 3)

Subsequent univariate ANCOVArsquos indicated signifi-cant differences between populations inhabiting differentislands on factors one (F13237 = 2426 P lt 0001) two(F13237 = 11315 P lt 0001) and three (F13237 =2476 P lt 0001) (Fig 2b) The individuals from thepopulation inhabiting the island ofHvar weremore often

associated with closed microhabitats were more oftenfound inside the shelters at greater heights and furtheraway from vegetation cover Individuals of the popu-lation from the island of Hvar were found on sub-strates like metal wood or plastic more often andwere more orientated toward western and southernexposures Age class differences were significant onfactors one (F13237 = 869 P = 0003) and two

Fig 1 Scatter plot illustrating the results of a factor analysisperformed on the microhabitat data for two species of geckos(Hemidactilus turcicus and Tarentola mauritanica) occurring insympatry on the island of Hvar

Table 3 Results of MANCOVA performed on micro-habitat dataduring a 24-h cycle for all seasons The level of significance used inanalysis was 005

Effect Wilksrsquo lambda df F P

MANCOVA on micro-habitat data for two species of geckos onthe island of HvarSpecies 075 3 2312 26171 lt0001Age classes 099 3 2312 415 0006Season (co-variate) 094 3 2312 4537 lt0001Species middot age classes 099 3 2312 408 0007MANCOVA on the factor scores on microhabitat data forallopatric and sympatric population of H turcicusIsland 095 3 3235 5398 lt0001Age classes 097 3 3235 2769 lt0001Season (co-variate) 087 3 3235 15554 lt0001Time of day (co-variate) 095 3 3235 5816 lt0001Species middot age classes 098 3 3235 2097 lt0001

Fig 2 Factor loadings values (y axis) resulting from factoranalyses with varimax rotation on microhabitat characteristicsillustrating differences in microhabitat utilisation a Graph illus-trating differences in microhabitat use between H turcicus and Tmauritanica on the island of Hvar b Graph illustrating differencesin microhabitat use between H turcicus occurring in sympatry withT mauritanica on island of Hvar versus in allopatry on island ofVis c Graph illustrating differences in habitat use of H turcicus ofdifferent age classes in sympatry and allopatry

555

(F13237 = 6766 P lt 0001) (Fig 2c) Adults on bothislands were found more often in closed microhabitatsinside hiding places at greater heights and at greaterdistance from vegetation However juveniles on bothislands chose substrates like metal wood plastic orother types of man-made debris more often Theseasonal effect was significant on factors one(F13237 = 2668 P lt 0001) two (F13237 = 9077P lt 0001) and three (F13237 = 6524 P lt 0001) Inaddition time of day was significant on factors one(F13237 = 16177 P lt 0001) and three (F13237 =859 P = 0003) This implies that both seasonalchanges and daytime cycle have a significant effect onmicrohabitat utilisation distance to hiding place andvegetation cover and the choice of height substrateand cardinal direction The two-way interactionbetween island and age class was significant on factorsone (F13237 = 2099 P lt 0001) two (F13237 =2364 P lt 0001) and three (F13237 = 1916 P lt0001) indicating that the age classes used differentmicrohabitats on the two islands

Discussion

A previous study on relative population densities com-paring T mauritanica and H turcicus indicated lowerpopulation densities of H turcicus in sympatry (Hvar)as compared to the populations in allopatry (Vis)Moreover populations in syntopy showed lower popu-lation densities than population in allotopy on the sameisland (Hvar) and allotopic populations on Hvarshowed lower densities than allopatric populations onVis indicating a strong effect of the presence of Tmauritanica on H turcicus (DL et al unpublisheddata) The results of the present study reveal differencesin habitat and microhabitat use of these same two gecko

species in sympatry Moreover differences in habitat usecan be demonstrated between populations of H turcicusin allopatry (Vis) versus those on Hvar in sympatry withT mauritanica (Fig 2)

Species differences in sympatry

Our results suggest differentiation in habitat use amongthese two species in sympatry (Table 3 Fig 2a) Differ-ences in microhabitat use in ecologically similar species insympatry are common (Reinert 1984 Kumstatova et al2004 Daly et al 2007 Yamauchi and Miki 2009 Chilloet al 2010) Although spatial segregation is often sug-gested as one of the mechanisms allowing the coexistencebetweendifferent species (Schoener 1974a b) it is unlikelythat sympatric species are completely spatially isolatedand in many cases some degree of spatial overlap doesoccur (Schoener 1983) Thus even if our data suggestsegregation on a small spatial scale between T maurita-nica and H turcicus in sympatry it is unlikely that com-petition does not occur at all More likely the reportedmicrohabitat differences function to decrease the com-petitive interactions between T mauritanica and H tur-cicus Moreover the observed differences in habitat usagemay stem from the species-specific biological require-ments as suggested previously (Gill et al 1994a b Punzo2001 Hitchcock and McBrayer 2006) Consequently theecological differences between these species may allowtheir coexistence in communal habitats A spatial nicheshift like that reported here has been observed previouslyin other sympatric associations of ecologically similarspecies (Schoener 1975 Pianka and Huey 1978 Grbacand Brnin 2006) Our data are similar to that reported forhabitat use in the tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric versus allopatric localities(Kumstatova et al 2004) These two related passerinesshow differences in habitat use in allopatry and expressniche shifts when occurring in sympatry similar to whatwe observed in our two studied geckos

Allopatric versus sympatric populations of H turcicus

Habitat divergence between allopatric and sympatricpopulations of H turcicus may originate from thepresence or absence of the potential competitor Tmauritanica (Table 3 Fig 2b) Previous studies on Tmauritanica and H turcicus in sympatry suggested sim-ilarity in niche occupation between species (Capula andLuiselli 1994 Luiselli and Capizzi 1999) Moreover ourdata on relative population densities suggests competi-tive interactions between T mauritanica and H turcicus(DL et al unpublished data) Although the habitatanalysis presented here suggests differences in spatialniche in sympatry to test whether the presence of apotential competitor affects habitat use one must com-pare populations in different competitive scenarios(sympatry vs allopatry) Our data show that H turcicus

Table 4 Factor loadings resulting from a factor analysis withvarimax rotation performed on the habitat data of geckos observedduring the 24-h cycle through all seasons for sympatric (Hvar) andallopatric (Vis) populations of H turcicus

Factor

1 2 3

Eigenvalue 4333 14 1018 of variance explained 4333 1400 1018Habitat 0087 0550 0011In-out 0903a 0131 0172Microhabitat 0861a 0244 0065Substrate 0089 0786a 0255Activity 0678 0379 0230Orientation 0280 0673 0073Height 0735a 0119 0439Log (inside-outside) (lower is inside) 0754a 0152 0306Log (dist to veg) (lower is under veg) 0766a 0285 0114Log (inclination plus) 0148 0134 0858a

aFactor loadings greater than 07

556

in allopatry uses all types of microhabitats needed tofulfil its ecological demands In sympatry H turcicuscan be observed more in closed habitats like water wellsand field cottages the types of habitat that are usuallyavoided by the heliophilous and more active T mauri-tanica Changes in spatial niche in allopatry as comparedto sympatry like that observed in this study have beenreported for a wide variety of taxa including insects(Honkavaara et al 2011) amphibians (Rice et al 2009)and birds (Kirschel et al 2009) and suggests that thismay be a general phenomenon However the observedhabitat difference in sympatric versus allopatric popu-lations of H turcicus may potentially be related to dif-ferences in available microhabitats between the twoislands Indeed islands show slight differences in fieldcottage and stonewall constructions As these differencesare generally minor and do not reflect the observeddifferences in habitat use it is likely that observed dif-ferences in spatial niche are driven by the presence ofcompetition between two ecologically similar specieswith T mauritanica being dominant over H turcicus

Intraspecific differences in habitat use

Interestingly in both species independent of the pres-ence of a potential competitor we observed differenthabitat use between age classes (Table 3) Juvenilegeckos more often used open habitats and venture intomicrohabitats rarely occupied by adults Other studieshave similarly demonstrated that juveniles differ inspatial niche from adult conspecifics (Blouin-Demerset al 2007) One of the arguments put forward to explainthis difference is the avoidance of predation by adults onjuveniles (Pough et al 2001) Alternatively avoidance ofcompetition with adults (Brischoux et al 2009) popu-lation dispersion strategies (Punzo 2001) or lack ofexperience in young animals have been suggested asexplanations for this pattern (Pough et al 2001) One ofthe most studied European lizard species Lacerta agilisshows similar ontogenic shifts in microhabitat usageYoung individuals typically use open habitats likemeadows while adults are usually found in vicinity ofbushes that can be used as shelters These differences inhabitat use suggest behavioural interactions betweenadults and juveniles Meadows do not provide enoughshelter for adult lizards and thick grass may disturb theirlocomotion while juveniles avoid habitats occupied byadults and find enough cover in meadows (Amat et al2003 Nemes et al 2006) The results of our study sug-gest that such behavioural strategies may also be em-ployed in the gecko species studied here Our results alsoindicate that the difference in microhabitat use betweenage classes in sympatry is species specific implying thatwhen occurring in the same habitat the two age classesof each species each have their unique requirementsresulting in a decrease in intra- but also interspeciescompetitive interactions In addition age class-relateddifferences in habitat use detected in H turcicus are

island specific This result implies a spatial niche shiftbetween age classes in H turcicus in the absence of thecompetitively superior T mauritanica

Interestingly not only is the habitat use in both ageclasses of H turcicus affected by the presence of T mau-ritanica but both age classes also show a shift in habitatuse in allopatry compared to sympatry (Fig 2c) Nichewidening in the absence of competition is a well-docu-mented phenomenon (Rice et al 2009) The habitat shiftobserved in this study illustrates how profound is theinfluence of the presence of the competitively superior Tmauritanica onH turcicus In many species the presenceof a sympatric heterospecific influences only one age classFor example a study on the interactions between twosimilar trout species implied negative competitive inter-actions in juveniles but not adults (McGrath and Lewis2007) Yet other studies indicate competitive interactionsoccurring principally between adults (Torok and Toth1999) In some cases interspecific age class-related inter-actions were reported with adults of one species influ-encing juveniles of the other species (Museth et al 2010)

The ability of H turcicus to adapt its habitatrequirements in both age classes may be an explanationfor its invasive potential This species is known to haveinvaded distant areas that are far outside its naturalgeographic area mostly by means of human-based dis-persal (Selcer 1986 Locey and Stone 2006) Our studyon spatial niche shifts suggests a potential origin of theecological plasticity allowing H turcicus to adapt to thenew environment Since in its native geographic rangeH turcicus often enters into competition with T mau-ritanica it would seem beneficial for H turcicus to retainsome level of plasticity that allows coexistence with acompetitively stronger heterospecifics Moreover ourresults suggest that this plasticity is characteristic of bothadults and juveniles

Effect of covariates (season and time of day)

Finally our results also indicate a significant seasonaleffect on the spatial niche utilisation between species insympatry as well as among populations of H turcicus insympatry versus allopatry Such a temporally fluctuatingutilisation of the available habitat has been reported formany different taxa (Pianka 1969 Ricklefs et al 1981Pough et al 2001) and may further impose demands onflexibility in habitat use

However it is important to point out the lack of asignificant effect of the time of the day in the sympatricpopulation on Hvar This implies that both species havesimilar behavioural patterns during the course of theday Nevertheless both species exhibit similar oscilla-tions in habitat utilisation showing greater movementsduring the night hours and staying near hiding placesduring daytime In addition both species demonstratepositive thermoregulatory behaviour during daytimehours but with different thermoregulatory strategies(direct sunlight basking vs convective heating) Inter-

557

estingly our results indicate difference in habitat util-isation between sympatric versus allopatric populationsof H turcicus This implies that two populations differnot only in the seasonal characteristics of habitat pref-erences but also in a way of habitat utilisation on a dailybasis Such differences could be the result of differentclimate and ecological characteristics between islandsbut are likely affected by the presence of another geckospecies on the island of Hvar

In summary the data presented here indicate habitatsegregation in sympatry as well as release of competitiverestraints in allopatry in the subordinate species Giventhe often complicated mechanisms of interspecies inter-actions and species co-existence (Ricklefs et al 1981Pough et al 2001 Merkle et al 2009) our data may addto a better understanding of these processes Whereasour data suggest effects of competition on habitat use in

H turcicus further studies including other componentsof the ecological niche such as diet and temperature areneeded to better understand the ecological strategies ofthis species that allow it to coexist with T mauritanica

Acknowledgements We thank all the people that participated in thefield work Many thanks to the families of Petar Zitko and TonciMaroevic for accommodation on the islands of Vis and HvarMany thanks to Pava and Simun Lisicic for their continued sup-port during the study This work was supported through grant No119-0000000-1285 of the Ministry of Science Education and Sportof the Republic of Croatia to ZT

Appendix

(See Table 5)

Table 5 Categories and subcategories of habitat used in measuring habitat utilisation forH turcicus and T mauritanica on island of Hvar(populations in sympatry) and island of Vis (H turcicus population in allopatry)

Category of habitat Sub-categoryof habitat

Description

Habitat General habitat typesWater wellField cottageField doors Specific constructions that include wooden doors two columns

and small roof above doors Intensively used by geckosWall All types of walls and stonewallsTreeColumn Power columns or field marks of column formNear to ground habitat Ground grass piles of rocks or twigs man-made debris

Position Outside Position inside or outside of shelter placeAt the entranceInside

Microhabitat Various types of microhabitat used by geckosOpen habitats Habitats that were open or offer minimal protection from

weather conditions and predatorsGroundLogStoneWallUnder stoneboardInside hole Shallow holes at open habitatsNear ceilingCeiling

Closed habitats Inside closed habitats that offers protection fromenvironmental conditions ie inside field cottage

WallBoardGroundUnder stoneboardInside holeIn crevice Crevices are defined as all types of holes deep enough that

geckos can hide from weather conditions and predatorsAnthropogenic debris Old clothes piles of twigs glasses old boxes with toolsNear ceilingceiling

Inside water well entrance Water well entrances usually used as warming spotsWallUnder panelPanel

Inside water well Very stable conditions ideal hiding places from weatherconditions

WallNear ceilingInside holeCeiling

558

References

Amat F Llorente GA Carretero MA (2003) A preliminary studyon thermal ecology activity times and microhabitat use ofLacerta agilis (Squamata Lacertidae) in the Pyrenees FoliaZool 52413ndash422

Arad Z Schwarzbaum A Werner Y (1997) Temperature selectionand thermoregulation in the Moorish gecko Tarentola mauri-tanica Amphibia Reptilia 69269ndash282

Arnold EN Ovenden D (2002) A field guide to the reptiles andamphibians of Britain and Europe 2nd edn Harper CollinsLondon

Atzori A Berti F Cencetti T Fornasiero S Tamburini M ZuffiMAL (2007) Advances in methodologies of sexing and markingless dimorphic gekkonid lizards the study case of the Moorishgecko Tarentola mauritanica Amphibia Reptilia 28449ndash454

Blouin-Demers G Bjorgan LPG Weatherhead PJ (2007) Changesin habitat use and movement patterns with body size in blackratsnakes (Elaphe obsoleta) Herpetologica 63421ndash429

Brecko J Huyghe K Vanhooydonck B Herrel A Grbac I VanDamme R (2008) Functional and ecological relevance ofintraspecific variation in body size and shape in a lizard Po-darcis melisellensis Biol J Linn Soc 94251ndash264

Brischoux F Bonnet X Shine R (2009) Determinants of dietaryspecialization a comparison of two sympatric species of seasnakes Oikos 118145ndash151

Capula M Luiselli L (1994) Tropic niche overlap in sympatricTarentola mauritanica and Hemidactylus turcicus a preliminarystudy Herpetol J 424ndash25

Carretero MA (2008) Preferred temperatures of Tarentola mauri-tanica in spring Acta Herpetol 357ndash64

Chillo V Rodrıguez D Ojeda AR (2010) Niche partitioning andcoexistence between two mammalian herbivores in the drychaco of Argentina Acta Oecol 36611ndash616

Daly BD Dickman CR Crowther MS (2007) Selection of habitatcomponents by two species of agamid lizards in sandridgedesert central Australia Austral Ecol 32825ndash833

Dangremond EM Pardini EA Knight TM (2010) Apparentcompetition with an invasive plant hastens the extinction of anendangered lupine Ecology 912261ndash2271

De PinhoWF Colli GR Vitt LJ (2009) Determinants of assemblagestructure in Neotropical dry forest lizards Aust Ecol 3497ndash115

Doughty P Shine R (1995) Life in two dimensions natural historyof the southern leaf-tailed gecko Phyllurus platurus Herpeto-logica 51193ndash201

Downes S Bauwens D (2002) An experimental demonstration ofdirect behavioural interference in two Mediterranean lacertidlizard species Anim Behav 631037ndash1046

Downes S Shine R (1998) Heat safety or solitude Using habitatselection experiments to identify a lizardrsquos priorities AnimBehav 551387ndash1396

Gill MJ Guerrero F Perez-Mellado V (1994a) Diel variation inpreferred body temperatures of the Moorish gecko Tarentolamauritanica during summer Herpetol J 456ndash59

Gill MJ Guerrero F Perez-Mellado V (1994b) Seasonal variationin diet composition and prey selection in the mediterraneangecko Tarentola mauritanica Isr J Zool 4061ndash74

Grbac I Brnin K (2006) Habitat use of sympatric populations ofPodarcis sicula and P melisellensis on a small Adriatic islandPeriod Biol 108177ndash182

Hitchcock MA McBrayer LD (2006) Thermoregulation in noc-turnal ectotherms seasonal and intraspecific variation in theMediterranean Gecko (Hemidactylus turcicus) J Herpetol40185ndash195

Hodar JA Pleguezuelos JM Villafranca C Frenandes-CardeneteJR (2006) Foraging mode of the Moorish gecko Tarentolamauritanica in an arid environment inferences from abioticsetting prey availability and dietary composition J AridEnviron 6583ndash93

Table 5 continued

Category of habitat Sub-categoryof habitat

Description

SubstrateOld clothPaperConcreteStone-concreteStoneWoodBrickPlastic glassMetalTileDirt grass

Type of behaviorStillStillactive Geckos found standing still outside the typical hiding places

ie on wall inside field cottage during cold dayActiveEatingWarmingStillwarming Inactive non-moving geckos that chose warming positions ie

inside water well entrance during winter monthsSun bathing

Cardinal directionNone Geckos found in the middle of field cottage or water well had

no general cardinal directionNorthEastWestSouth

559

Honkavaara J Dunn DW Ilvonen S Suhonen J (2011) Sympatricshift in a male sexual ornament in the damselfly Calopteryxsplendens J Evol Biol 24139ndash145 doi101111j1420-9101201002146x

Huey RB Pianka ER (1977) Patterns of niche overlap amongbroadly sympatric versus narrowly sympatric Kalahari lizards(Scincidae Mabuya) Ecology 5819ndash28

Hunt JFG Bonsall MB (2009) The effects of colonization extinc-tion and competition on co-existence in metacommunitiesJ Anim Ecol 78866ndash879

Johnson J McBrayer LD Saenz D (2005) Allometry sexual sizedimorphism and niche partitioning in the Mediterranean gecko(Hemidactylus turcicus) Southwest Nat 50435ndash439 doi1018940038-4909(2005)050[0435ASSDAN]20CO2

Kirschel ANG Blumstein DT Smith TB (2009) Character dis-placement of song and morphology in African tinkerbirds ProcNatl Acad Sci USA 1068256ndash8261

Kjoss V Litvaitis J (2001) Community structure of snakes in ahuman-dominated landscape Biol Conserv 98285ndash292

Kumstatova T Brinke T Tomkova S Fuchs R Petrusek A (2004)Habitat preferences of tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric and allopatric localitiesJ Ornithol 145334ndash342 doi101007s10336-004-0048-3

Lima A Moreira G (1993) Effects of prey size and foraging modeon the ontogenetic change in feeding niche of Colostethusstephani (Anura Dendrobatidae) Oecologia 9593ndash120

Locey KJ Stone PA (2006) Factors affecting range expansion inthe introduced Mediterranean gecko Hemidactylus turcicusJ Herpetol 40526ndash530

Luh HK Pimm SL (1993) The assembly of ecological communitiesa minimalist approach J Anim Ecol 62749ndash765

Luiselli L (2006) Resource partitioning and interspecific competi-tion in snakes the search for general geographical and guildpatterns Oikos 114193ndash211

Luiselli L Capizzi D (1999) Ecological distribution of the geckosTarentola mauritanica and Hemidactylus turcicus in the urbanarea of Rome in relation to age of buildings and condition ofthe walls J Herpetol 33316ndash319

Marquet PA Bozinovic F Medel RG Werner YL Jaksic FM(1990) Ecology of Garthia gaudichaudi a gecko endemic to thesemiarid region of Chile J Herpetol 24431ndash434

McGrath CC Lewis WM Jr (2007) Competition and predation asmechanisms for displacement of Greenback Cutthroat Trout byBrook Trout Trans Am Fish Soc 1361381ndash1392

Merkle JA Stahler DR Smith DW (2009) Interference competitionbetween gray wolves and coyotes in Yellowstone NationalPark Can J Zool 8756ndash63

Museth J Borgstroslashm R Brittain JE (2010) Diet overlap betweenintroduced European minnow (Phoxinus phoxinus) and youngbrown trout (Salmo trutta) in the lake Oslashvre Heimdalsvatn aresult of abundantresources or forced niche overlap Hydrobi-ologia 64293ndash100 doi101007s10750-010-0162-6

Nemes S Vogrin M Hartel T Ollerer K (2006) Habitat selection atthe sand lizard (Lacerta agilis) ontogenetic shifts N West JZool 217ndash26

Pianka ER (1969) Sympatry of desert lizards (Ctenotus) in WesternAustralia Ecology 501012ndash1030

Pianka ER (1974) Niche overlap and diffuse competition ProcNatl Acad Sci USA 712141ndash2145

Pianka ER Huey RB (1978) Comparative ecology resource util-isation and niche segregation among gekkonid lizards in theSouthern Kalahari Copeia 4691ndash701

Pough FH Andrews RM Cadle JE Crump ML Savitzky AHWells KD (2001) Herpetology 2nd edn Prentice-Hall Engle-wood Cliffs NJ

Punzo F (2001) The Mediterranean gecko Hemidactylus turcicuslife in an urban landscape Fla Sci 6456ndash66

Reinert HK (1984) Habitat variation within sympatric snakepopulations Ecology 651673ndash1682

Rice AM Leichty AR Pfennig DW (2009) Parallel evolution andecological selection replicated character displacement inspadefoot toads Proc R Soc B 2764189ndash4196 doi101098rspb20091337

Ricklefs RE Cochran D Pianka ER (1981) A morphologicalanalysis of the structure of communities of lizards in deserthabitats Ecology 621474ndash1483

Schoener TW (1974a) The compression hypothesis and temporalresource partitioning Proc Natl Acad Sci USA 714169ndash4172

Schoener TW (1974b) Resource partitioning in ecological com-munities Science 18527ndash39

Schoener TW (1975) Presence and absence of habitat shift in somewidespread lizard species Ecol Monogr 45233ndash258

Schoener TW (1983) Field experiments on interspecific competi-tion Am Nat 122240ndash285

Schoener TW Losos JB Spiller DA (2005) Island biogeography ofpopulations an introduced species transform survival patternsScience 3101807ndash1809 doi101126science1120165

Selcer KW (1986) Life history of a successful colonizer the Med-iterranean gecko Hemidactylus turcicus in Southern TexasCopeia 4956ndash962

Torok J Toth L (1999) Asymmetric competition between two titspecies a reciprocial removal experiment J Anim Ecol68338ndash345

Vitt LJ Zani PA (1998) Prey use among sympatric lizard species inlowland rain forest of Nicaragua J Trop Ecol 14537ndash559

Werner YL Takahashi H Mautz WJ Ota H (2005) Behavior ofthe terrestrial nocturnal lizards Goniurosaurus kuroiwae ku-roiwae and Eublepharis macularius (Reptilia Eublepharidae) ina thigmothermal gradient J Ther Biol 30247ndash254 doi101016jjtherbio200412004

Yamauchi A Miki T (2009) Intraspecific niche flexibility facilitatesspecies coexistence in a competitive community with a fluctu-ating environment Oikos 11855ndash66

560

6752 of the variation in the data (Table 4) In-outmicrohabitat height and distance to vegetation werestrongly positively correlated while distance to hidingplace was strongly negatively correlated with the firstfactor Substrate was strongly positively correlated withsecond factor and inclination was strongly positivelycorrelated with the third factor

A MANCOVA performed on the factor scores onmicrohabitat data for allopatric and sympatric popula-tions of H turcicus indicated significant differences be-tween populations on different islands and age classeswith significant seasonal (co-variate) and time of day(co-variate) effects The two-way interaction betweenislands and age classes was also significant (Table 3)

Subsequent univariate ANCOVArsquos indicated signifi-cant differences between populations inhabiting differentislands on factors one (F13237 = 2426 P lt 0001) two(F13237 = 11315 P lt 0001) and three (F13237 =2476 P lt 0001) (Fig 2b) The individuals from thepopulation inhabiting the island ofHvar weremore often

associated with closed microhabitats were more oftenfound inside the shelters at greater heights and furtheraway from vegetation cover Individuals of the popu-lation from the island of Hvar were found on sub-strates like metal wood or plastic more often andwere more orientated toward western and southernexposures Age class differences were significant onfactors one (F13237 = 869 P = 0003) and two

Fig 1 Scatter plot illustrating the results of a factor analysisperformed on the microhabitat data for two species of geckos(Hemidactilus turcicus and Tarentola mauritanica) occurring insympatry on the island of Hvar

Table 3 Results of MANCOVA performed on micro-habitat dataduring a 24-h cycle for all seasons The level of significance used inanalysis was 005

Effect Wilksrsquo lambda df F P

MANCOVA on micro-habitat data for two species of geckos onthe island of HvarSpecies 075 3 2312 26171 lt0001Age classes 099 3 2312 415 0006Season (co-variate) 094 3 2312 4537 lt0001Species middot age classes 099 3 2312 408 0007MANCOVA on the factor scores on microhabitat data forallopatric and sympatric population of H turcicusIsland 095 3 3235 5398 lt0001Age classes 097 3 3235 2769 lt0001Season (co-variate) 087 3 3235 15554 lt0001Time of day (co-variate) 095 3 3235 5816 lt0001Species middot age classes 098 3 3235 2097 lt0001

Fig 2 Factor loadings values (y axis) resulting from factoranalyses with varimax rotation on microhabitat characteristicsillustrating differences in microhabitat utilisation a Graph illus-trating differences in microhabitat use between H turcicus and Tmauritanica on the island of Hvar b Graph illustrating differencesin microhabitat use between H turcicus occurring in sympatry withT mauritanica on island of Hvar versus in allopatry on island ofVis c Graph illustrating differences in habitat use of H turcicus ofdifferent age classes in sympatry and allopatry

555

(F13237 = 6766 P lt 0001) (Fig 2c) Adults on bothislands were found more often in closed microhabitatsinside hiding places at greater heights and at greaterdistance from vegetation However juveniles on bothislands chose substrates like metal wood plastic orother types of man-made debris more often Theseasonal effect was significant on factors one(F13237 = 2668 P lt 0001) two (F13237 = 9077P lt 0001) and three (F13237 = 6524 P lt 0001) Inaddition time of day was significant on factors one(F13237 = 16177 P lt 0001) and three (F13237 =859 P = 0003) This implies that both seasonalchanges and daytime cycle have a significant effect onmicrohabitat utilisation distance to hiding place andvegetation cover and the choice of height substrateand cardinal direction The two-way interactionbetween island and age class was significant on factorsone (F13237 = 2099 P lt 0001) two (F13237 =2364 P lt 0001) and three (F13237 = 1916 P lt0001) indicating that the age classes used differentmicrohabitats on the two islands

Discussion

A previous study on relative population densities com-paring T mauritanica and H turcicus indicated lowerpopulation densities of H turcicus in sympatry (Hvar)as compared to the populations in allopatry (Vis)Moreover populations in syntopy showed lower popu-lation densities than population in allotopy on the sameisland (Hvar) and allotopic populations on Hvarshowed lower densities than allopatric populations onVis indicating a strong effect of the presence of Tmauritanica on H turcicus (DL et al unpublisheddata) The results of the present study reveal differencesin habitat and microhabitat use of these same two gecko

species in sympatry Moreover differences in habitat usecan be demonstrated between populations of H turcicusin allopatry (Vis) versus those on Hvar in sympatry withT mauritanica (Fig 2)

Species differences in sympatry

Our results suggest differentiation in habitat use amongthese two species in sympatry (Table 3 Fig 2a) Differ-ences in microhabitat use in ecologically similar species insympatry are common (Reinert 1984 Kumstatova et al2004 Daly et al 2007 Yamauchi and Miki 2009 Chilloet al 2010) Although spatial segregation is often sug-gested as one of the mechanisms allowing the coexistencebetweendifferent species (Schoener 1974a b) it is unlikelythat sympatric species are completely spatially isolatedand in many cases some degree of spatial overlap doesoccur (Schoener 1983) Thus even if our data suggestsegregation on a small spatial scale between T maurita-nica and H turcicus in sympatry it is unlikely that com-petition does not occur at all More likely the reportedmicrohabitat differences function to decrease the com-petitive interactions between T mauritanica and H tur-cicus Moreover the observed differences in habitat usagemay stem from the species-specific biological require-ments as suggested previously (Gill et al 1994a b Punzo2001 Hitchcock and McBrayer 2006) Consequently theecological differences between these species may allowtheir coexistence in communal habitats A spatial nicheshift like that reported here has been observed previouslyin other sympatric associations of ecologically similarspecies (Schoener 1975 Pianka and Huey 1978 Grbacand Brnin 2006) Our data are similar to that reported forhabitat use in the tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric versus allopatric localities(Kumstatova et al 2004) These two related passerinesshow differences in habitat use in allopatry and expressniche shifts when occurring in sympatry similar to whatwe observed in our two studied geckos

Allopatric versus sympatric populations of H turcicus

Habitat divergence between allopatric and sympatricpopulations of H turcicus may originate from thepresence or absence of the potential competitor Tmauritanica (Table 3 Fig 2b) Previous studies on Tmauritanica and H turcicus in sympatry suggested sim-ilarity in niche occupation between species (Capula andLuiselli 1994 Luiselli and Capizzi 1999) Moreover ourdata on relative population densities suggests competi-tive interactions between T mauritanica and H turcicus(DL et al unpublished data) Although the habitatanalysis presented here suggests differences in spatialniche in sympatry to test whether the presence of apotential competitor affects habitat use one must com-pare populations in different competitive scenarios(sympatry vs allopatry) Our data show that H turcicus

Table 4 Factor loadings resulting from a factor analysis withvarimax rotation performed on the habitat data of geckos observedduring the 24-h cycle through all seasons for sympatric (Hvar) andallopatric (Vis) populations of H turcicus

Factor

1 2 3

Eigenvalue 4333 14 1018 of variance explained 4333 1400 1018Habitat 0087 0550 0011In-out 0903a 0131 0172Microhabitat 0861a 0244 0065Substrate 0089 0786a 0255Activity 0678 0379 0230Orientation 0280 0673 0073Height 0735a 0119 0439Log (inside-outside) (lower is inside) 0754a 0152 0306Log (dist to veg) (lower is under veg) 0766a 0285 0114Log (inclination plus) 0148 0134 0858a

aFactor loadings greater than 07

556

in allopatry uses all types of microhabitats needed tofulfil its ecological demands In sympatry H turcicuscan be observed more in closed habitats like water wellsand field cottages the types of habitat that are usuallyavoided by the heliophilous and more active T mauri-tanica Changes in spatial niche in allopatry as comparedto sympatry like that observed in this study have beenreported for a wide variety of taxa including insects(Honkavaara et al 2011) amphibians (Rice et al 2009)and birds (Kirschel et al 2009) and suggests that thismay be a general phenomenon However the observedhabitat difference in sympatric versus allopatric popu-lations of H turcicus may potentially be related to dif-ferences in available microhabitats between the twoislands Indeed islands show slight differences in fieldcottage and stonewall constructions As these differencesare generally minor and do not reflect the observeddifferences in habitat use it is likely that observed dif-ferences in spatial niche are driven by the presence ofcompetition between two ecologically similar specieswith T mauritanica being dominant over H turcicus

Intraspecific differences in habitat use

Interestingly in both species independent of the pres-ence of a potential competitor we observed differenthabitat use between age classes (Table 3) Juvenilegeckos more often used open habitats and venture intomicrohabitats rarely occupied by adults Other studieshave similarly demonstrated that juveniles differ inspatial niche from adult conspecifics (Blouin-Demerset al 2007) One of the arguments put forward to explainthis difference is the avoidance of predation by adults onjuveniles (Pough et al 2001) Alternatively avoidance ofcompetition with adults (Brischoux et al 2009) popu-lation dispersion strategies (Punzo 2001) or lack ofexperience in young animals have been suggested asexplanations for this pattern (Pough et al 2001) One ofthe most studied European lizard species Lacerta agilisshows similar ontogenic shifts in microhabitat usageYoung individuals typically use open habitats likemeadows while adults are usually found in vicinity ofbushes that can be used as shelters These differences inhabitat use suggest behavioural interactions betweenadults and juveniles Meadows do not provide enoughshelter for adult lizards and thick grass may disturb theirlocomotion while juveniles avoid habitats occupied byadults and find enough cover in meadows (Amat et al2003 Nemes et al 2006) The results of our study sug-gest that such behavioural strategies may also be em-ployed in the gecko species studied here Our results alsoindicate that the difference in microhabitat use betweenage classes in sympatry is species specific implying thatwhen occurring in the same habitat the two age classesof each species each have their unique requirementsresulting in a decrease in intra- but also interspeciescompetitive interactions In addition age class-relateddifferences in habitat use detected in H turcicus are

island specific This result implies a spatial niche shiftbetween age classes in H turcicus in the absence of thecompetitively superior T mauritanica

Interestingly not only is the habitat use in both ageclasses of H turcicus affected by the presence of T mau-ritanica but both age classes also show a shift in habitatuse in allopatry compared to sympatry (Fig 2c) Nichewidening in the absence of competition is a well-docu-mented phenomenon (Rice et al 2009) The habitat shiftobserved in this study illustrates how profound is theinfluence of the presence of the competitively superior Tmauritanica onH turcicus In many species the presenceof a sympatric heterospecific influences only one age classFor example a study on the interactions between twosimilar trout species implied negative competitive inter-actions in juveniles but not adults (McGrath and Lewis2007) Yet other studies indicate competitive interactionsoccurring principally between adults (Torok and Toth1999) In some cases interspecific age class-related inter-actions were reported with adults of one species influ-encing juveniles of the other species (Museth et al 2010)

The ability of H turcicus to adapt its habitatrequirements in both age classes may be an explanationfor its invasive potential This species is known to haveinvaded distant areas that are far outside its naturalgeographic area mostly by means of human-based dis-persal (Selcer 1986 Locey and Stone 2006) Our studyon spatial niche shifts suggests a potential origin of theecological plasticity allowing H turcicus to adapt to thenew environment Since in its native geographic rangeH turcicus often enters into competition with T mau-ritanica it would seem beneficial for H turcicus to retainsome level of plasticity that allows coexistence with acompetitively stronger heterospecifics Moreover ourresults suggest that this plasticity is characteristic of bothadults and juveniles

Effect of covariates (season and time of day)

Finally our results also indicate a significant seasonaleffect on the spatial niche utilisation between species insympatry as well as among populations of H turcicus insympatry versus allopatry Such a temporally fluctuatingutilisation of the available habitat has been reported formany different taxa (Pianka 1969 Ricklefs et al 1981Pough et al 2001) and may further impose demands onflexibility in habitat use

However it is important to point out the lack of asignificant effect of the time of the day in the sympatricpopulation on Hvar This implies that both species havesimilar behavioural patterns during the course of theday Nevertheless both species exhibit similar oscilla-tions in habitat utilisation showing greater movementsduring the night hours and staying near hiding placesduring daytime In addition both species demonstratepositive thermoregulatory behaviour during daytimehours but with different thermoregulatory strategies(direct sunlight basking vs convective heating) Inter-

557

estingly our results indicate difference in habitat util-isation between sympatric versus allopatric populationsof H turcicus This implies that two populations differnot only in the seasonal characteristics of habitat pref-erences but also in a way of habitat utilisation on a dailybasis Such differences could be the result of differentclimate and ecological characteristics between islandsbut are likely affected by the presence of another geckospecies on the island of Hvar

In summary the data presented here indicate habitatsegregation in sympatry as well as release of competitiverestraints in allopatry in the subordinate species Giventhe often complicated mechanisms of interspecies inter-actions and species co-existence (Ricklefs et al 1981Pough et al 2001 Merkle et al 2009) our data may addto a better understanding of these processes Whereasour data suggest effects of competition on habitat use in

H turcicus further studies including other componentsof the ecological niche such as diet and temperature areneeded to better understand the ecological strategies ofthis species that allow it to coexist with T mauritanica

Acknowledgements We thank all the people that participated in thefield work Many thanks to the families of Petar Zitko and TonciMaroevic for accommodation on the islands of Vis and HvarMany thanks to Pava and Simun Lisicic for their continued sup-port during the study This work was supported through grant No119-0000000-1285 of the Ministry of Science Education and Sportof the Republic of Croatia to ZT

Appendix

(See Table 5)

Table 5 Categories and subcategories of habitat used in measuring habitat utilisation forH turcicus and T mauritanica on island of Hvar(populations in sympatry) and island of Vis (H turcicus population in allopatry)

Category of habitat Sub-categoryof habitat

Description

Habitat General habitat typesWater wellField cottageField doors Specific constructions that include wooden doors two columns

and small roof above doors Intensively used by geckosWall All types of walls and stonewallsTreeColumn Power columns or field marks of column formNear to ground habitat Ground grass piles of rocks or twigs man-made debris

Position Outside Position inside or outside of shelter placeAt the entranceInside

Microhabitat Various types of microhabitat used by geckosOpen habitats Habitats that were open or offer minimal protection from

weather conditions and predatorsGroundLogStoneWallUnder stoneboardInside hole Shallow holes at open habitatsNear ceilingCeiling

Closed habitats Inside closed habitats that offers protection fromenvironmental conditions ie inside field cottage

WallBoardGroundUnder stoneboardInside holeIn crevice Crevices are defined as all types of holes deep enough that

geckos can hide from weather conditions and predatorsAnthropogenic debris Old clothes piles of twigs glasses old boxes with toolsNear ceilingceiling

Inside water well entrance Water well entrances usually used as warming spotsWallUnder panelPanel

Inside water well Very stable conditions ideal hiding places from weatherconditions

WallNear ceilingInside holeCeiling

558

References

Amat F Llorente GA Carretero MA (2003) A preliminary studyon thermal ecology activity times and microhabitat use ofLacerta agilis (Squamata Lacertidae) in the Pyrenees FoliaZool 52413ndash422

Arad Z Schwarzbaum A Werner Y (1997) Temperature selectionand thermoregulation in the Moorish gecko Tarentola mauri-tanica Amphibia Reptilia 69269ndash282

Arnold EN Ovenden D (2002) A field guide to the reptiles andamphibians of Britain and Europe 2nd edn Harper CollinsLondon

Atzori A Berti F Cencetti T Fornasiero S Tamburini M ZuffiMAL (2007) Advances in methodologies of sexing and markingless dimorphic gekkonid lizards the study case of the Moorishgecko Tarentola mauritanica Amphibia Reptilia 28449ndash454

Blouin-Demers G Bjorgan LPG Weatherhead PJ (2007) Changesin habitat use and movement patterns with body size in blackratsnakes (Elaphe obsoleta) Herpetologica 63421ndash429

Brecko J Huyghe K Vanhooydonck B Herrel A Grbac I VanDamme R (2008) Functional and ecological relevance ofintraspecific variation in body size and shape in a lizard Po-darcis melisellensis Biol J Linn Soc 94251ndash264

Brischoux F Bonnet X Shine R (2009) Determinants of dietaryspecialization a comparison of two sympatric species of seasnakes Oikos 118145ndash151

Capula M Luiselli L (1994) Tropic niche overlap in sympatricTarentola mauritanica and Hemidactylus turcicus a preliminarystudy Herpetol J 424ndash25

Carretero MA (2008) Preferred temperatures of Tarentola mauri-tanica in spring Acta Herpetol 357ndash64

Chillo V Rodrıguez D Ojeda AR (2010) Niche partitioning andcoexistence between two mammalian herbivores in the drychaco of Argentina Acta Oecol 36611ndash616

Daly BD Dickman CR Crowther MS (2007) Selection of habitatcomponents by two species of agamid lizards in sandridgedesert central Australia Austral Ecol 32825ndash833

Dangremond EM Pardini EA Knight TM (2010) Apparentcompetition with an invasive plant hastens the extinction of anendangered lupine Ecology 912261ndash2271

De PinhoWF Colli GR Vitt LJ (2009) Determinants of assemblagestructure in Neotropical dry forest lizards Aust Ecol 3497ndash115

Doughty P Shine R (1995) Life in two dimensions natural historyof the southern leaf-tailed gecko Phyllurus platurus Herpeto-logica 51193ndash201

Downes S Bauwens D (2002) An experimental demonstration ofdirect behavioural interference in two Mediterranean lacertidlizard species Anim Behav 631037ndash1046

Downes S Shine R (1998) Heat safety or solitude Using habitatselection experiments to identify a lizardrsquos priorities AnimBehav 551387ndash1396

Gill MJ Guerrero F Perez-Mellado V (1994a) Diel variation inpreferred body temperatures of the Moorish gecko Tarentolamauritanica during summer Herpetol J 456ndash59

Gill MJ Guerrero F Perez-Mellado V (1994b) Seasonal variationin diet composition and prey selection in the mediterraneangecko Tarentola mauritanica Isr J Zool 4061ndash74

Grbac I Brnin K (2006) Habitat use of sympatric populations ofPodarcis sicula and P melisellensis on a small Adriatic islandPeriod Biol 108177ndash182

Hitchcock MA McBrayer LD (2006) Thermoregulation in noc-turnal ectotherms seasonal and intraspecific variation in theMediterranean Gecko (Hemidactylus turcicus) J Herpetol40185ndash195

Hodar JA Pleguezuelos JM Villafranca C Frenandes-CardeneteJR (2006) Foraging mode of the Moorish gecko Tarentolamauritanica in an arid environment inferences from abioticsetting prey availability and dietary composition J AridEnviron 6583ndash93

Table 5 continued

Category of habitat Sub-categoryof habitat

Description

SubstrateOld clothPaperConcreteStone-concreteStoneWoodBrickPlastic glassMetalTileDirt grass

Type of behaviorStillStillactive Geckos found standing still outside the typical hiding places

ie on wall inside field cottage during cold dayActiveEatingWarmingStillwarming Inactive non-moving geckos that chose warming positions ie

inside water well entrance during winter monthsSun bathing

Cardinal directionNone Geckos found in the middle of field cottage or water well had

no general cardinal directionNorthEastWestSouth

559

Honkavaara J Dunn DW Ilvonen S Suhonen J (2011) Sympatricshift in a male sexual ornament in the damselfly Calopteryxsplendens J Evol Biol 24139ndash145 doi101111j1420-9101201002146x

Huey RB Pianka ER (1977) Patterns of niche overlap amongbroadly sympatric versus narrowly sympatric Kalahari lizards(Scincidae Mabuya) Ecology 5819ndash28

Hunt JFG Bonsall MB (2009) The effects of colonization extinc-tion and competition on co-existence in metacommunitiesJ Anim Ecol 78866ndash879

Johnson J McBrayer LD Saenz D (2005) Allometry sexual sizedimorphism and niche partitioning in the Mediterranean gecko(Hemidactylus turcicus) Southwest Nat 50435ndash439 doi1018940038-4909(2005)050[0435ASSDAN]20CO2

Kirschel ANG Blumstein DT Smith TB (2009) Character dis-placement of song and morphology in African tinkerbirds ProcNatl Acad Sci USA 1068256ndash8261

Kjoss V Litvaitis J (2001) Community structure of snakes in ahuman-dominated landscape Biol Conserv 98285ndash292

Kumstatova T Brinke T Tomkova S Fuchs R Petrusek A (2004)Habitat preferences of tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric and allopatric localitiesJ Ornithol 145334ndash342 doi101007s10336-004-0048-3

Lima A Moreira G (1993) Effects of prey size and foraging modeon the ontogenetic change in feeding niche of Colostethusstephani (Anura Dendrobatidae) Oecologia 9593ndash120

Locey KJ Stone PA (2006) Factors affecting range expansion inthe introduced Mediterranean gecko Hemidactylus turcicusJ Herpetol 40526ndash530

Luh HK Pimm SL (1993) The assembly of ecological communitiesa minimalist approach J Anim Ecol 62749ndash765

Luiselli L (2006) Resource partitioning and interspecific competi-tion in snakes the search for general geographical and guildpatterns Oikos 114193ndash211

Luiselli L Capizzi D (1999) Ecological distribution of the geckosTarentola mauritanica and Hemidactylus turcicus in the urbanarea of Rome in relation to age of buildings and condition ofthe walls J Herpetol 33316ndash319

Marquet PA Bozinovic F Medel RG Werner YL Jaksic FM(1990) Ecology of Garthia gaudichaudi a gecko endemic to thesemiarid region of Chile J Herpetol 24431ndash434

McGrath CC Lewis WM Jr (2007) Competition and predation asmechanisms for displacement of Greenback Cutthroat Trout byBrook Trout Trans Am Fish Soc 1361381ndash1392

Merkle JA Stahler DR Smith DW (2009) Interference competitionbetween gray wolves and coyotes in Yellowstone NationalPark Can J Zool 8756ndash63

Museth J Borgstroslashm R Brittain JE (2010) Diet overlap betweenintroduced European minnow (Phoxinus phoxinus) and youngbrown trout (Salmo trutta) in the lake Oslashvre Heimdalsvatn aresult of abundantresources or forced niche overlap Hydrobi-ologia 64293ndash100 doi101007s10750-010-0162-6

Nemes S Vogrin M Hartel T Ollerer K (2006) Habitat selection atthe sand lizard (Lacerta agilis) ontogenetic shifts N West JZool 217ndash26

Pianka ER (1969) Sympatry of desert lizards (Ctenotus) in WesternAustralia Ecology 501012ndash1030

Pianka ER (1974) Niche overlap and diffuse competition ProcNatl Acad Sci USA 712141ndash2145

Pianka ER Huey RB (1978) Comparative ecology resource util-isation and niche segregation among gekkonid lizards in theSouthern Kalahari Copeia 4691ndash701

Pough FH Andrews RM Cadle JE Crump ML Savitzky AHWells KD (2001) Herpetology 2nd edn Prentice-Hall Engle-wood Cliffs NJ

Punzo F (2001) The Mediterranean gecko Hemidactylus turcicuslife in an urban landscape Fla Sci 6456ndash66

Reinert HK (1984) Habitat variation within sympatric snakepopulations Ecology 651673ndash1682

Rice AM Leichty AR Pfennig DW (2009) Parallel evolution andecological selection replicated character displacement inspadefoot toads Proc R Soc B 2764189ndash4196 doi101098rspb20091337

Ricklefs RE Cochran D Pianka ER (1981) A morphologicalanalysis of the structure of communities of lizards in deserthabitats Ecology 621474ndash1483

Schoener TW (1974a) The compression hypothesis and temporalresource partitioning Proc Natl Acad Sci USA 714169ndash4172

Schoener TW (1974b) Resource partitioning in ecological com-munities Science 18527ndash39

Schoener TW (1975) Presence and absence of habitat shift in somewidespread lizard species Ecol Monogr 45233ndash258

Schoener TW (1983) Field experiments on interspecific competi-tion Am Nat 122240ndash285

Schoener TW Losos JB Spiller DA (2005) Island biogeography ofpopulations an introduced species transform survival patternsScience 3101807ndash1809 doi101126science1120165

Selcer KW (1986) Life history of a successful colonizer the Med-iterranean gecko Hemidactylus turcicus in Southern TexasCopeia 4956ndash962

Torok J Toth L (1999) Asymmetric competition between two titspecies a reciprocial removal experiment J Anim Ecol68338ndash345

Vitt LJ Zani PA (1998) Prey use among sympatric lizard species inlowland rain forest of Nicaragua J Trop Ecol 14537ndash559

Werner YL Takahashi H Mautz WJ Ota H (2005) Behavior ofthe terrestrial nocturnal lizards Goniurosaurus kuroiwae ku-roiwae and Eublepharis macularius (Reptilia Eublepharidae) ina thigmothermal gradient J Ther Biol 30247ndash254 doi101016jjtherbio200412004

Yamauchi A Miki T (2009) Intraspecific niche flexibility facilitatesspecies coexistence in a competitive community with a fluctu-ating environment Oikos 11855ndash66

560

(F13237 = 6766 P lt 0001) (Fig 2c) Adults on bothislands were found more often in closed microhabitatsinside hiding places at greater heights and at greaterdistance from vegetation However juveniles on bothislands chose substrates like metal wood plastic orother types of man-made debris more often Theseasonal effect was significant on factors one(F13237 = 2668 P lt 0001) two (F13237 = 9077P lt 0001) and three (F13237 = 6524 P lt 0001) Inaddition time of day was significant on factors one(F13237 = 16177 P lt 0001) and three (F13237 =859 P = 0003) This implies that both seasonalchanges and daytime cycle have a significant effect onmicrohabitat utilisation distance to hiding place andvegetation cover and the choice of height substrateand cardinal direction The two-way interactionbetween island and age class was significant on factorsone (F13237 = 2099 P lt 0001) two (F13237 =2364 P lt 0001) and three (F13237 = 1916 P lt0001) indicating that the age classes used differentmicrohabitats on the two islands

Discussion

A previous study on relative population densities com-paring T mauritanica and H turcicus indicated lowerpopulation densities of H turcicus in sympatry (Hvar)as compared to the populations in allopatry (Vis)Moreover populations in syntopy showed lower popu-lation densities than population in allotopy on the sameisland (Hvar) and allotopic populations on Hvarshowed lower densities than allopatric populations onVis indicating a strong effect of the presence of Tmauritanica on H turcicus (DL et al unpublisheddata) The results of the present study reveal differencesin habitat and microhabitat use of these same two gecko

species in sympatry Moreover differences in habitat usecan be demonstrated between populations of H turcicusin allopatry (Vis) versus those on Hvar in sympatry withT mauritanica (Fig 2)

Species differences in sympatry

Our results suggest differentiation in habitat use amongthese two species in sympatry (Table 3 Fig 2a) Differ-ences in microhabitat use in ecologically similar species insympatry are common (Reinert 1984 Kumstatova et al2004 Daly et al 2007 Yamauchi and Miki 2009 Chilloet al 2010) Although spatial segregation is often sug-gested as one of the mechanisms allowing the coexistencebetweendifferent species (Schoener 1974a b) it is unlikelythat sympatric species are completely spatially isolatedand in many cases some degree of spatial overlap doesoccur (Schoener 1983) Thus even if our data suggestsegregation on a small spatial scale between T maurita-nica and H turcicus in sympatry it is unlikely that com-petition does not occur at all More likely the reportedmicrohabitat differences function to decrease the com-petitive interactions between T mauritanica and H tur-cicus Moreover the observed differences in habitat usagemay stem from the species-specific biological require-ments as suggested previously (Gill et al 1994a b Punzo2001 Hitchcock and McBrayer 2006) Consequently theecological differences between these species may allowtheir coexistence in communal habitats A spatial nicheshift like that reported here has been observed previouslyin other sympatric associations of ecologically similarspecies (Schoener 1975 Pianka and Huey 1978 Grbacand Brnin 2006) Our data are similar to that reported forhabitat use in the tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric versus allopatric localities(Kumstatova et al 2004) These two related passerinesshow differences in habitat use in allopatry and expressniche shifts when occurring in sympatry similar to whatwe observed in our two studied geckos

Allopatric versus sympatric populations of H turcicus

Habitat divergence between allopatric and sympatricpopulations of H turcicus may originate from thepresence or absence of the potential competitor Tmauritanica (Table 3 Fig 2b) Previous studies on Tmauritanica and H turcicus in sympatry suggested sim-ilarity in niche occupation between species (Capula andLuiselli 1994 Luiselli and Capizzi 1999) Moreover ourdata on relative population densities suggests competi-tive interactions between T mauritanica and H turcicus(DL et al unpublished data) Although the habitatanalysis presented here suggests differences in spatialniche in sympatry to test whether the presence of apotential competitor affects habitat use one must com-pare populations in different competitive scenarios(sympatry vs allopatry) Our data show that H turcicus

Table 4 Factor loadings resulting from a factor analysis withvarimax rotation performed on the habitat data of geckos observedduring the 24-h cycle through all seasons for sympatric (Hvar) andallopatric (Vis) populations of H turcicus

Factor

1 2 3

Eigenvalue 4333 14 1018 of variance explained 4333 1400 1018Habitat 0087 0550 0011In-out 0903a 0131 0172Microhabitat 0861a 0244 0065Substrate 0089 0786a 0255Activity 0678 0379 0230Orientation 0280 0673 0073Height 0735a 0119 0439Log (inside-outside) (lower is inside) 0754a 0152 0306Log (dist to veg) (lower is under veg) 0766a 0285 0114Log (inclination plus) 0148 0134 0858a

aFactor loadings greater than 07

556

in allopatry uses all types of microhabitats needed tofulfil its ecological demands In sympatry H turcicuscan be observed more in closed habitats like water wellsand field cottages the types of habitat that are usuallyavoided by the heliophilous and more active T mauri-tanica Changes in spatial niche in allopatry as comparedto sympatry like that observed in this study have beenreported for a wide variety of taxa including insects(Honkavaara et al 2011) amphibians (Rice et al 2009)and birds (Kirschel et al 2009) and suggests that thismay be a general phenomenon However the observedhabitat difference in sympatric versus allopatric popu-lations of H turcicus may potentially be related to dif-ferences in available microhabitats between the twoislands Indeed islands show slight differences in fieldcottage and stonewall constructions As these differencesare generally minor and do not reflect the observeddifferences in habitat use it is likely that observed dif-ferences in spatial niche are driven by the presence ofcompetition between two ecologically similar specieswith T mauritanica being dominant over H turcicus

Intraspecific differences in habitat use

Interestingly in both species independent of the pres-ence of a potential competitor we observed differenthabitat use between age classes (Table 3) Juvenilegeckos more often used open habitats and venture intomicrohabitats rarely occupied by adults Other studieshave similarly demonstrated that juveniles differ inspatial niche from adult conspecifics (Blouin-Demerset al 2007) One of the arguments put forward to explainthis difference is the avoidance of predation by adults onjuveniles (Pough et al 2001) Alternatively avoidance ofcompetition with adults (Brischoux et al 2009) popu-lation dispersion strategies (Punzo 2001) or lack ofexperience in young animals have been suggested asexplanations for this pattern (Pough et al 2001) One ofthe most studied European lizard species Lacerta agilisshows similar ontogenic shifts in microhabitat usageYoung individuals typically use open habitats likemeadows while adults are usually found in vicinity ofbushes that can be used as shelters These differences inhabitat use suggest behavioural interactions betweenadults and juveniles Meadows do not provide enoughshelter for adult lizards and thick grass may disturb theirlocomotion while juveniles avoid habitats occupied byadults and find enough cover in meadows (Amat et al2003 Nemes et al 2006) The results of our study sug-gest that such behavioural strategies may also be em-ployed in the gecko species studied here Our results alsoindicate that the difference in microhabitat use betweenage classes in sympatry is species specific implying thatwhen occurring in the same habitat the two age classesof each species each have their unique requirementsresulting in a decrease in intra- but also interspeciescompetitive interactions In addition age class-relateddifferences in habitat use detected in H turcicus are

island specific This result implies a spatial niche shiftbetween age classes in H turcicus in the absence of thecompetitively superior T mauritanica

Interestingly not only is the habitat use in both ageclasses of H turcicus affected by the presence of T mau-ritanica but both age classes also show a shift in habitatuse in allopatry compared to sympatry (Fig 2c) Nichewidening in the absence of competition is a well-docu-mented phenomenon (Rice et al 2009) The habitat shiftobserved in this study illustrates how profound is theinfluence of the presence of the competitively superior Tmauritanica onH turcicus In many species the presenceof a sympatric heterospecific influences only one age classFor example a study on the interactions between twosimilar trout species implied negative competitive inter-actions in juveniles but not adults (McGrath and Lewis2007) Yet other studies indicate competitive interactionsoccurring principally between adults (Torok and Toth1999) In some cases interspecific age class-related inter-actions were reported with adults of one species influ-encing juveniles of the other species (Museth et al 2010)

The ability of H turcicus to adapt its habitatrequirements in both age classes may be an explanationfor its invasive potential This species is known to haveinvaded distant areas that are far outside its naturalgeographic area mostly by means of human-based dis-persal (Selcer 1986 Locey and Stone 2006) Our studyon spatial niche shifts suggests a potential origin of theecological plasticity allowing H turcicus to adapt to thenew environment Since in its native geographic rangeH turcicus often enters into competition with T mau-ritanica it would seem beneficial for H turcicus to retainsome level of plasticity that allows coexistence with acompetitively stronger heterospecifics Moreover ourresults suggest that this plasticity is characteristic of bothadults and juveniles

Effect of covariates (season and time of day)

Finally our results also indicate a significant seasonaleffect on the spatial niche utilisation between species insympatry as well as among populations of H turcicus insympatry versus allopatry Such a temporally fluctuatingutilisation of the available habitat has been reported formany different taxa (Pianka 1969 Ricklefs et al 1981Pough et al 2001) and may further impose demands onflexibility in habitat use

However it is important to point out the lack of asignificant effect of the time of the day in the sympatricpopulation on Hvar This implies that both species havesimilar behavioural patterns during the course of theday Nevertheless both species exhibit similar oscilla-tions in habitat utilisation showing greater movementsduring the night hours and staying near hiding placesduring daytime In addition both species demonstratepositive thermoregulatory behaviour during daytimehours but with different thermoregulatory strategies(direct sunlight basking vs convective heating) Inter-

557

estingly our results indicate difference in habitat util-isation between sympatric versus allopatric populationsof H turcicus This implies that two populations differnot only in the seasonal characteristics of habitat pref-erences but also in a way of habitat utilisation on a dailybasis Such differences could be the result of differentclimate and ecological characteristics between islandsbut are likely affected by the presence of another geckospecies on the island of Hvar

In summary the data presented here indicate habitatsegregation in sympatry as well as release of competitiverestraints in allopatry in the subordinate species Giventhe often complicated mechanisms of interspecies inter-actions and species co-existence (Ricklefs et al 1981Pough et al 2001 Merkle et al 2009) our data may addto a better understanding of these processes Whereasour data suggest effects of competition on habitat use in

H turcicus further studies including other componentsof the ecological niche such as diet and temperature areneeded to better understand the ecological strategies ofthis species that allow it to coexist with T mauritanica

Acknowledgements We thank all the people that participated in thefield work Many thanks to the families of Petar Zitko and TonciMaroevic for accommodation on the islands of Vis and HvarMany thanks to Pava and Simun Lisicic for their continued sup-port during the study This work was supported through grant No119-0000000-1285 of the Ministry of Science Education and Sportof the Republic of Croatia to ZT

Appendix

(See Table 5)

Table 5 Categories and subcategories of habitat used in measuring habitat utilisation forH turcicus and T mauritanica on island of Hvar(populations in sympatry) and island of Vis (H turcicus population in allopatry)

Category of habitat Sub-categoryof habitat

Description

Habitat General habitat typesWater wellField cottageField doors Specific constructions that include wooden doors two columns

and small roof above doors Intensively used by geckosWall All types of walls and stonewallsTreeColumn Power columns or field marks of column formNear to ground habitat Ground grass piles of rocks or twigs man-made debris

Position Outside Position inside or outside of shelter placeAt the entranceInside

Microhabitat Various types of microhabitat used by geckosOpen habitats Habitats that were open or offer minimal protection from

weather conditions and predatorsGroundLogStoneWallUnder stoneboardInside hole Shallow holes at open habitatsNear ceilingCeiling

Closed habitats Inside closed habitats that offers protection fromenvironmental conditions ie inside field cottage

WallBoardGroundUnder stoneboardInside holeIn crevice Crevices are defined as all types of holes deep enough that

geckos can hide from weather conditions and predatorsAnthropogenic debris Old clothes piles of twigs glasses old boxes with toolsNear ceilingceiling

Inside water well entrance Water well entrances usually used as warming spotsWallUnder panelPanel

Inside water well Very stable conditions ideal hiding places from weatherconditions

WallNear ceilingInside holeCeiling

558

References

Amat F Llorente GA Carretero MA (2003) A preliminary studyon thermal ecology activity times and microhabitat use ofLacerta agilis (Squamata Lacertidae) in the Pyrenees FoliaZool 52413ndash422

Arad Z Schwarzbaum A Werner Y (1997) Temperature selectionand thermoregulation in the Moorish gecko Tarentola mauri-tanica Amphibia Reptilia 69269ndash282

Arnold EN Ovenden D (2002) A field guide to the reptiles andamphibians of Britain and Europe 2nd edn Harper CollinsLondon

Atzori A Berti F Cencetti T Fornasiero S Tamburini M ZuffiMAL (2007) Advances in methodologies of sexing and markingless dimorphic gekkonid lizards the study case of the Moorishgecko Tarentola mauritanica Amphibia Reptilia 28449ndash454

Blouin-Demers G Bjorgan LPG Weatherhead PJ (2007) Changesin habitat use and movement patterns with body size in blackratsnakes (Elaphe obsoleta) Herpetologica 63421ndash429

Brecko J Huyghe K Vanhooydonck B Herrel A Grbac I VanDamme R (2008) Functional and ecological relevance ofintraspecific variation in body size and shape in a lizard Po-darcis melisellensis Biol J Linn Soc 94251ndash264

Brischoux F Bonnet X Shine R (2009) Determinants of dietaryspecialization a comparison of two sympatric species of seasnakes Oikos 118145ndash151

Capula M Luiselli L (1994) Tropic niche overlap in sympatricTarentola mauritanica and Hemidactylus turcicus a preliminarystudy Herpetol J 424ndash25

Carretero MA (2008) Preferred temperatures of Tarentola mauri-tanica in spring Acta Herpetol 357ndash64

Chillo V Rodrıguez D Ojeda AR (2010) Niche partitioning andcoexistence between two mammalian herbivores in the drychaco of Argentina Acta Oecol 36611ndash616

Daly BD Dickman CR Crowther MS (2007) Selection of habitatcomponents by two species of agamid lizards in sandridgedesert central Australia Austral Ecol 32825ndash833

Dangremond EM Pardini EA Knight TM (2010) Apparentcompetition with an invasive plant hastens the extinction of anendangered lupine Ecology 912261ndash2271

De PinhoWF Colli GR Vitt LJ (2009) Determinants of assemblagestructure in Neotropical dry forest lizards Aust Ecol 3497ndash115

Doughty P Shine R (1995) Life in two dimensions natural historyof the southern leaf-tailed gecko Phyllurus platurus Herpeto-logica 51193ndash201

Downes S Bauwens D (2002) An experimental demonstration ofdirect behavioural interference in two Mediterranean lacertidlizard species Anim Behav 631037ndash1046

Downes S Shine R (1998) Heat safety or solitude Using habitatselection experiments to identify a lizardrsquos priorities AnimBehav 551387ndash1396

Gill MJ Guerrero F Perez-Mellado V (1994a) Diel variation inpreferred body temperatures of the Moorish gecko Tarentolamauritanica during summer Herpetol J 456ndash59

Gill MJ Guerrero F Perez-Mellado V (1994b) Seasonal variationin diet composition and prey selection in the mediterraneangecko Tarentola mauritanica Isr J Zool 4061ndash74

Grbac I Brnin K (2006) Habitat use of sympatric populations ofPodarcis sicula and P melisellensis on a small Adriatic islandPeriod Biol 108177ndash182

Hitchcock MA McBrayer LD (2006) Thermoregulation in noc-turnal ectotherms seasonal and intraspecific variation in theMediterranean Gecko (Hemidactylus turcicus) J Herpetol40185ndash195

Hodar JA Pleguezuelos JM Villafranca C Frenandes-CardeneteJR (2006) Foraging mode of the Moorish gecko Tarentolamauritanica in an arid environment inferences from abioticsetting prey availability and dietary composition J AridEnviron 6583ndash93

Table 5 continued

Category of habitat Sub-categoryof habitat

Description

SubstrateOld clothPaperConcreteStone-concreteStoneWoodBrickPlastic glassMetalTileDirt grass

Type of behaviorStillStillactive Geckos found standing still outside the typical hiding places

ie on wall inside field cottage during cold dayActiveEatingWarmingStillwarming Inactive non-moving geckos that chose warming positions ie

inside water well entrance during winter monthsSun bathing

Cardinal directionNone Geckos found in the middle of field cottage or water well had

no general cardinal directionNorthEastWestSouth

559

Honkavaara J Dunn DW Ilvonen S Suhonen J (2011) Sympatricshift in a male sexual ornament in the damselfly Calopteryxsplendens J Evol Biol 24139ndash145 doi101111j1420-9101201002146x

Huey RB Pianka ER (1977) Patterns of niche overlap amongbroadly sympatric versus narrowly sympatric Kalahari lizards(Scincidae Mabuya) Ecology 5819ndash28

Hunt JFG Bonsall MB (2009) The effects of colonization extinc-tion and competition on co-existence in metacommunitiesJ Anim Ecol 78866ndash879

Johnson J McBrayer LD Saenz D (2005) Allometry sexual sizedimorphism and niche partitioning in the Mediterranean gecko(Hemidactylus turcicus) Southwest Nat 50435ndash439 doi1018940038-4909(2005)050[0435ASSDAN]20CO2

Kirschel ANG Blumstein DT Smith TB (2009) Character dis-placement of song and morphology in African tinkerbirds ProcNatl Acad Sci USA 1068256ndash8261

Kjoss V Litvaitis J (2001) Community structure of snakes in ahuman-dominated landscape Biol Conserv 98285ndash292

Kumstatova T Brinke T Tomkova S Fuchs R Petrusek A (2004)Habitat preferences of tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric and allopatric localitiesJ Ornithol 145334ndash342 doi101007s10336-004-0048-3

Lima A Moreira G (1993) Effects of prey size and foraging modeon the ontogenetic change in feeding niche of Colostethusstephani (Anura Dendrobatidae) Oecologia 9593ndash120

Locey KJ Stone PA (2006) Factors affecting range expansion inthe introduced Mediterranean gecko Hemidactylus turcicusJ Herpetol 40526ndash530

Luh HK Pimm SL (1993) The assembly of ecological communitiesa minimalist approach J Anim Ecol 62749ndash765

Luiselli L (2006) Resource partitioning and interspecific competi-tion in snakes the search for general geographical and guildpatterns Oikos 114193ndash211

Luiselli L Capizzi D (1999) Ecological distribution of the geckosTarentola mauritanica and Hemidactylus turcicus in the urbanarea of Rome in relation to age of buildings and condition ofthe walls J Herpetol 33316ndash319

Marquet PA Bozinovic F Medel RG Werner YL Jaksic FM(1990) Ecology of Garthia gaudichaudi a gecko endemic to thesemiarid region of Chile J Herpetol 24431ndash434

McGrath CC Lewis WM Jr (2007) Competition and predation asmechanisms for displacement of Greenback Cutthroat Trout byBrook Trout Trans Am Fish Soc 1361381ndash1392

Merkle JA Stahler DR Smith DW (2009) Interference competitionbetween gray wolves and coyotes in Yellowstone NationalPark Can J Zool 8756ndash63

Museth J Borgstroslashm R Brittain JE (2010) Diet overlap betweenintroduced European minnow (Phoxinus phoxinus) and youngbrown trout (Salmo trutta) in the lake Oslashvre Heimdalsvatn aresult of abundantresources or forced niche overlap Hydrobi-ologia 64293ndash100 doi101007s10750-010-0162-6

Nemes S Vogrin M Hartel T Ollerer K (2006) Habitat selection atthe sand lizard (Lacerta agilis) ontogenetic shifts N West JZool 217ndash26

Pianka ER (1969) Sympatry of desert lizards (Ctenotus) in WesternAustralia Ecology 501012ndash1030

Pianka ER (1974) Niche overlap and diffuse competition ProcNatl Acad Sci USA 712141ndash2145

Pianka ER Huey RB (1978) Comparative ecology resource util-isation and niche segregation among gekkonid lizards in theSouthern Kalahari Copeia 4691ndash701

Pough FH Andrews RM Cadle JE Crump ML Savitzky AHWells KD (2001) Herpetology 2nd edn Prentice-Hall Engle-wood Cliffs NJ

Punzo F (2001) The Mediterranean gecko Hemidactylus turcicuslife in an urban landscape Fla Sci 6456ndash66

Reinert HK (1984) Habitat variation within sympatric snakepopulations Ecology 651673ndash1682

Rice AM Leichty AR Pfennig DW (2009) Parallel evolution andecological selection replicated character displacement inspadefoot toads Proc R Soc B 2764189ndash4196 doi101098rspb20091337

Ricklefs RE Cochran D Pianka ER (1981) A morphologicalanalysis of the structure of communities of lizards in deserthabitats Ecology 621474ndash1483

Schoener TW (1974a) The compression hypothesis and temporalresource partitioning Proc Natl Acad Sci USA 714169ndash4172

Schoener TW (1974b) Resource partitioning in ecological com-munities Science 18527ndash39

Schoener TW (1975) Presence and absence of habitat shift in somewidespread lizard species Ecol Monogr 45233ndash258

Schoener TW (1983) Field experiments on interspecific competi-tion Am Nat 122240ndash285

Schoener TW Losos JB Spiller DA (2005) Island biogeography ofpopulations an introduced species transform survival patternsScience 3101807ndash1809 doi101126science1120165

Selcer KW (1986) Life history of a successful colonizer the Med-iterranean gecko Hemidactylus turcicus in Southern TexasCopeia 4956ndash962

Torok J Toth L (1999) Asymmetric competition between two titspecies a reciprocial removal experiment J Anim Ecol68338ndash345

Vitt LJ Zani PA (1998) Prey use among sympatric lizard species inlowland rain forest of Nicaragua J Trop Ecol 14537ndash559

Werner YL Takahashi H Mautz WJ Ota H (2005) Behavior ofthe terrestrial nocturnal lizards Goniurosaurus kuroiwae ku-roiwae and Eublepharis macularius (Reptilia Eublepharidae) ina thigmothermal gradient J Ther Biol 30247ndash254 doi101016jjtherbio200412004

Yamauchi A Miki T (2009) Intraspecific niche flexibility facilitatesspecies coexistence in a competitive community with a fluctu-ating environment Oikos 11855ndash66

560

in allopatry uses all types of microhabitats needed tofulfil its ecological demands In sympatry H turcicuscan be observed more in closed habitats like water wellsand field cottages the types of habitat that are usuallyavoided by the heliophilous and more active T mauri-tanica Changes in spatial niche in allopatry as comparedto sympatry like that observed in this study have beenreported for a wide variety of taxa including insects(Honkavaara et al 2011) amphibians (Rice et al 2009)and birds (Kirschel et al 2009) and suggests that thismay be a general phenomenon However the observedhabitat difference in sympatric versus allopatric popu-lations of H turcicus may potentially be related to dif-ferences in available microhabitats between the twoislands Indeed islands show slight differences in fieldcottage and stonewall constructions As these differencesare generally minor and do not reflect the observeddifferences in habitat use it is likely that observed dif-ferences in spatial niche are driven by the presence ofcompetition between two ecologically similar specieswith T mauritanica being dominant over H turcicus

Intraspecific differences in habitat use

Interestingly in both species independent of the pres-ence of a potential competitor we observed differenthabitat use between age classes (Table 3) Juvenilegeckos more often used open habitats and venture intomicrohabitats rarely occupied by adults Other studieshave similarly demonstrated that juveniles differ inspatial niche from adult conspecifics (Blouin-Demerset al 2007) One of the arguments put forward to explainthis difference is the avoidance of predation by adults onjuveniles (Pough et al 2001) Alternatively avoidance ofcompetition with adults (Brischoux et al 2009) popu-lation dispersion strategies (Punzo 2001) or lack ofexperience in young animals have been suggested asexplanations for this pattern (Pough et al 2001) One ofthe most studied European lizard species Lacerta agilisshows similar ontogenic shifts in microhabitat usageYoung individuals typically use open habitats likemeadows while adults are usually found in vicinity ofbushes that can be used as shelters These differences inhabitat use suggest behavioural interactions betweenadults and juveniles Meadows do not provide enoughshelter for adult lizards and thick grass may disturb theirlocomotion while juveniles avoid habitats occupied byadults and find enough cover in meadows (Amat et al2003 Nemes et al 2006) The results of our study sug-gest that such behavioural strategies may also be em-ployed in the gecko species studied here Our results alsoindicate that the difference in microhabitat use betweenage classes in sympatry is species specific implying thatwhen occurring in the same habitat the two age classesof each species each have their unique requirementsresulting in a decrease in intra- but also interspeciescompetitive interactions In addition age class-relateddifferences in habitat use detected in H turcicus are

island specific This result implies a spatial niche shiftbetween age classes in H turcicus in the absence of thecompetitively superior T mauritanica

Interestingly not only is the habitat use in both ageclasses of H turcicus affected by the presence of T mau-ritanica but both age classes also show a shift in habitatuse in allopatry compared to sympatry (Fig 2c) Nichewidening in the absence of competition is a well-docu-mented phenomenon (Rice et al 2009) The habitat shiftobserved in this study illustrates how profound is theinfluence of the presence of the competitively superior Tmauritanica onH turcicus In many species the presenceof a sympatric heterospecific influences only one age classFor example a study on the interactions between twosimilar trout species implied negative competitive inter-actions in juveniles but not adults (McGrath and Lewis2007) Yet other studies indicate competitive interactionsoccurring principally between adults (Torok and Toth1999) In some cases interspecific age class-related inter-actions were reported with adults of one species influ-encing juveniles of the other species (Museth et al 2010)

The ability of H turcicus to adapt its habitatrequirements in both age classes may be an explanationfor its invasive potential This species is known to haveinvaded distant areas that are far outside its naturalgeographic area mostly by means of human-based dis-persal (Selcer 1986 Locey and Stone 2006) Our studyon spatial niche shifts suggests a potential origin of theecological plasticity allowing H turcicus to adapt to thenew environment Since in its native geographic rangeH turcicus often enters into competition with T mau-ritanica it would seem beneficial for H turcicus to retainsome level of plasticity that allows coexistence with acompetitively stronger heterospecifics Moreover ourresults suggest that this plasticity is characteristic of bothadults and juveniles

Effect of covariates (season and time of day)

Finally our results also indicate a significant seasonaleffect on the spatial niche utilisation between species insympatry as well as among populations of H turcicus insympatry versus allopatry Such a temporally fluctuatingutilisation of the available habitat has been reported formany different taxa (Pianka 1969 Ricklefs et al 1981Pough et al 2001) and may further impose demands onflexibility in habitat use

However it is important to point out the lack of asignificant effect of the time of the day in the sympatricpopulation on Hvar This implies that both species havesimilar behavioural patterns during the course of theday Nevertheless both species exhibit similar oscilla-tions in habitat utilisation showing greater movementsduring the night hours and staying near hiding placesduring daytime In addition both species demonstratepositive thermoregulatory behaviour during daytimehours but with different thermoregulatory strategies(direct sunlight basking vs convective heating) Inter-

557

estingly our results indicate difference in habitat util-isation between sympatric versus allopatric populationsof H turcicus This implies that two populations differnot only in the seasonal characteristics of habitat pref-erences but also in a way of habitat utilisation on a dailybasis Such differences could be the result of differentclimate and ecological characteristics between islandsbut are likely affected by the presence of another geckospecies on the island of Hvar

In summary the data presented here indicate habitatsegregation in sympatry as well as release of competitiverestraints in allopatry in the subordinate species Giventhe often complicated mechanisms of interspecies inter-actions and species co-existence (Ricklefs et al 1981Pough et al 2001 Merkle et al 2009) our data may addto a better understanding of these processes Whereasour data suggest effects of competition on habitat use in

H turcicus further studies including other componentsof the ecological niche such as diet and temperature areneeded to better understand the ecological strategies ofthis species that allow it to coexist with T mauritanica

Acknowledgements We thank all the people that participated in thefield work Many thanks to the families of Petar Zitko and TonciMaroevic for accommodation on the islands of Vis and HvarMany thanks to Pava and Simun Lisicic for their continued sup-port during the study This work was supported through grant No119-0000000-1285 of the Ministry of Science Education and Sportof the Republic of Croatia to ZT

Appendix

(See Table 5)

Table 5 Categories and subcategories of habitat used in measuring habitat utilisation forH turcicus and T mauritanica on island of Hvar(populations in sympatry) and island of Vis (H turcicus population in allopatry)

Category of habitat Sub-categoryof habitat

Description

Habitat General habitat typesWater wellField cottageField doors Specific constructions that include wooden doors two columns

and small roof above doors Intensively used by geckosWall All types of walls and stonewallsTreeColumn Power columns or field marks of column formNear to ground habitat Ground grass piles of rocks or twigs man-made debris

Position Outside Position inside or outside of shelter placeAt the entranceInside

Microhabitat Various types of microhabitat used by geckosOpen habitats Habitats that were open or offer minimal protection from

weather conditions and predatorsGroundLogStoneWallUnder stoneboardInside hole Shallow holes at open habitatsNear ceilingCeiling

Closed habitats Inside closed habitats that offers protection fromenvironmental conditions ie inside field cottage

WallBoardGroundUnder stoneboardInside holeIn crevice Crevices are defined as all types of holes deep enough that

geckos can hide from weather conditions and predatorsAnthropogenic debris Old clothes piles of twigs glasses old boxes with toolsNear ceilingceiling

Inside water well entrance Water well entrances usually used as warming spotsWallUnder panelPanel

Inside water well Very stable conditions ideal hiding places from weatherconditions

WallNear ceilingInside holeCeiling

558

References

Amat F Llorente GA Carretero MA (2003) A preliminary studyon thermal ecology activity times and microhabitat use ofLacerta agilis (Squamata Lacertidae) in the Pyrenees FoliaZool 52413ndash422

Arad Z Schwarzbaum A Werner Y (1997) Temperature selectionand thermoregulation in the Moorish gecko Tarentola mauri-tanica Amphibia Reptilia 69269ndash282

Arnold EN Ovenden D (2002) A field guide to the reptiles andamphibians of Britain and Europe 2nd edn Harper CollinsLondon

Atzori A Berti F Cencetti T Fornasiero S Tamburini M ZuffiMAL (2007) Advances in methodologies of sexing and markingless dimorphic gekkonid lizards the study case of the Moorishgecko Tarentola mauritanica Amphibia Reptilia 28449ndash454

Blouin-Demers G Bjorgan LPG Weatherhead PJ (2007) Changesin habitat use and movement patterns with body size in blackratsnakes (Elaphe obsoleta) Herpetologica 63421ndash429

Brecko J Huyghe K Vanhooydonck B Herrel A Grbac I VanDamme R (2008) Functional and ecological relevance ofintraspecific variation in body size and shape in a lizard Po-darcis melisellensis Biol J Linn Soc 94251ndash264

Brischoux F Bonnet X Shine R (2009) Determinants of dietaryspecialization a comparison of two sympatric species of seasnakes Oikos 118145ndash151

Capula M Luiselli L (1994) Tropic niche overlap in sympatricTarentola mauritanica and Hemidactylus turcicus a preliminarystudy Herpetol J 424ndash25

Carretero MA (2008) Preferred temperatures of Tarentola mauri-tanica in spring Acta Herpetol 357ndash64

Chillo V Rodrıguez D Ojeda AR (2010) Niche partitioning andcoexistence between two mammalian herbivores in the drychaco of Argentina Acta Oecol 36611ndash616

Daly BD Dickman CR Crowther MS (2007) Selection of habitatcomponents by two species of agamid lizards in sandridgedesert central Australia Austral Ecol 32825ndash833

Dangremond EM Pardini EA Knight TM (2010) Apparentcompetition with an invasive plant hastens the extinction of anendangered lupine Ecology 912261ndash2271

De PinhoWF Colli GR Vitt LJ (2009) Determinants of assemblagestructure in Neotropical dry forest lizards Aust Ecol 3497ndash115

Doughty P Shine R (1995) Life in two dimensions natural historyof the southern leaf-tailed gecko Phyllurus platurus Herpeto-logica 51193ndash201

Downes S Bauwens D (2002) An experimental demonstration ofdirect behavioural interference in two Mediterranean lacertidlizard species Anim Behav 631037ndash1046

Downes S Shine R (1998) Heat safety or solitude Using habitatselection experiments to identify a lizardrsquos priorities AnimBehav 551387ndash1396

Gill MJ Guerrero F Perez-Mellado V (1994a) Diel variation inpreferred body temperatures of the Moorish gecko Tarentolamauritanica during summer Herpetol J 456ndash59

Gill MJ Guerrero F Perez-Mellado V (1994b) Seasonal variationin diet composition and prey selection in the mediterraneangecko Tarentola mauritanica Isr J Zool 4061ndash74

Grbac I Brnin K (2006) Habitat use of sympatric populations ofPodarcis sicula and P melisellensis on a small Adriatic islandPeriod Biol 108177ndash182

Hitchcock MA McBrayer LD (2006) Thermoregulation in noc-turnal ectotherms seasonal and intraspecific variation in theMediterranean Gecko (Hemidactylus turcicus) J Herpetol40185ndash195

Hodar JA Pleguezuelos JM Villafranca C Frenandes-CardeneteJR (2006) Foraging mode of the Moorish gecko Tarentolamauritanica in an arid environment inferences from abioticsetting prey availability and dietary composition J AridEnviron 6583ndash93

Table 5 continued

Category of habitat Sub-categoryof habitat

Description

SubstrateOld clothPaperConcreteStone-concreteStoneWoodBrickPlastic glassMetalTileDirt grass

Type of behaviorStillStillactive Geckos found standing still outside the typical hiding places

ie on wall inside field cottage during cold dayActiveEatingWarmingStillwarming Inactive non-moving geckos that chose warming positions ie

inside water well entrance during winter monthsSun bathing

Cardinal directionNone Geckos found in the middle of field cottage or water well had

no general cardinal directionNorthEastWestSouth

559

Honkavaara J Dunn DW Ilvonen S Suhonen J (2011) Sympatricshift in a male sexual ornament in the damselfly Calopteryxsplendens J Evol Biol 24139ndash145 doi101111j1420-9101201002146x

Huey RB Pianka ER (1977) Patterns of niche overlap amongbroadly sympatric versus narrowly sympatric Kalahari lizards(Scincidae Mabuya) Ecology 5819ndash28

Hunt JFG Bonsall MB (2009) The effects of colonization extinc-tion and competition on co-existence in metacommunitiesJ Anim Ecol 78866ndash879

Johnson J McBrayer LD Saenz D (2005) Allometry sexual sizedimorphism and niche partitioning in the Mediterranean gecko(Hemidactylus turcicus) Southwest Nat 50435ndash439 doi1018940038-4909(2005)050[0435ASSDAN]20CO2

Kirschel ANG Blumstein DT Smith TB (2009) Character dis-placement of song and morphology in African tinkerbirds ProcNatl Acad Sci USA 1068256ndash8261

Kjoss V Litvaitis J (2001) Community structure of snakes in ahuman-dominated landscape Biol Conserv 98285ndash292

Kumstatova T Brinke T Tomkova S Fuchs R Petrusek A (2004)Habitat preferences of tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric and allopatric localitiesJ Ornithol 145334ndash342 doi101007s10336-004-0048-3

Lima A Moreira G (1993) Effects of prey size and foraging modeon the ontogenetic change in feeding niche of Colostethusstephani (Anura Dendrobatidae) Oecologia 9593ndash120

Locey KJ Stone PA (2006) Factors affecting range expansion inthe introduced Mediterranean gecko Hemidactylus turcicusJ Herpetol 40526ndash530

Luh HK Pimm SL (1993) The assembly of ecological communitiesa minimalist approach J Anim Ecol 62749ndash765

Luiselli L (2006) Resource partitioning and interspecific competi-tion in snakes the search for general geographical and guildpatterns Oikos 114193ndash211

Luiselli L Capizzi D (1999) Ecological distribution of the geckosTarentola mauritanica and Hemidactylus turcicus in the urbanarea of Rome in relation to age of buildings and condition ofthe walls J Herpetol 33316ndash319

Marquet PA Bozinovic F Medel RG Werner YL Jaksic FM(1990) Ecology of Garthia gaudichaudi a gecko endemic to thesemiarid region of Chile J Herpetol 24431ndash434

McGrath CC Lewis WM Jr (2007) Competition and predation asmechanisms for displacement of Greenback Cutthroat Trout byBrook Trout Trans Am Fish Soc 1361381ndash1392

Merkle JA Stahler DR Smith DW (2009) Interference competitionbetween gray wolves and coyotes in Yellowstone NationalPark Can J Zool 8756ndash63

Museth J Borgstroslashm R Brittain JE (2010) Diet overlap betweenintroduced European minnow (Phoxinus phoxinus) and youngbrown trout (Salmo trutta) in the lake Oslashvre Heimdalsvatn aresult of abundantresources or forced niche overlap Hydrobi-ologia 64293ndash100 doi101007s10750-010-0162-6

Nemes S Vogrin M Hartel T Ollerer K (2006) Habitat selection atthe sand lizard (Lacerta agilis) ontogenetic shifts N West JZool 217ndash26

Pianka ER (1969) Sympatry of desert lizards (Ctenotus) in WesternAustralia Ecology 501012ndash1030

Pianka ER (1974) Niche overlap and diffuse competition ProcNatl Acad Sci USA 712141ndash2145

Pianka ER Huey RB (1978) Comparative ecology resource util-isation and niche segregation among gekkonid lizards in theSouthern Kalahari Copeia 4691ndash701

Pough FH Andrews RM Cadle JE Crump ML Savitzky AHWells KD (2001) Herpetology 2nd edn Prentice-Hall Engle-wood Cliffs NJ

Punzo F (2001) The Mediterranean gecko Hemidactylus turcicuslife in an urban landscape Fla Sci 6456ndash66

Reinert HK (1984) Habitat variation within sympatric snakepopulations Ecology 651673ndash1682

Rice AM Leichty AR Pfennig DW (2009) Parallel evolution andecological selection replicated character displacement inspadefoot toads Proc R Soc B 2764189ndash4196 doi101098rspb20091337

Ricklefs RE Cochran D Pianka ER (1981) A morphologicalanalysis of the structure of communities of lizards in deserthabitats Ecology 621474ndash1483

Schoener TW (1974a) The compression hypothesis and temporalresource partitioning Proc Natl Acad Sci USA 714169ndash4172

Schoener TW (1974b) Resource partitioning in ecological com-munities Science 18527ndash39

Schoener TW (1975) Presence and absence of habitat shift in somewidespread lizard species Ecol Monogr 45233ndash258

Schoener TW (1983) Field experiments on interspecific competi-tion Am Nat 122240ndash285

Schoener TW Losos JB Spiller DA (2005) Island biogeography ofpopulations an introduced species transform survival patternsScience 3101807ndash1809 doi101126science1120165

Selcer KW (1986) Life history of a successful colonizer the Med-iterranean gecko Hemidactylus turcicus in Southern TexasCopeia 4956ndash962

Torok J Toth L (1999) Asymmetric competition between two titspecies a reciprocial removal experiment J Anim Ecol68338ndash345

Vitt LJ Zani PA (1998) Prey use among sympatric lizard species inlowland rain forest of Nicaragua J Trop Ecol 14537ndash559

Werner YL Takahashi H Mautz WJ Ota H (2005) Behavior ofthe terrestrial nocturnal lizards Goniurosaurus kuroiwae ku-roiwae and Eublepharis macularius (Reptilia Eublepharidae) ina thigmothermal gradient J Ther Biol 30247ndash254 doi101016jjtherbio200412004

Yamauchi A Miki T (2009) Intraspecific niche flexibility facilitatesspecies coexistence in a competitive community with a fluctu-ating environment Oikos 11855ndash66

560

estingly our results indicate difference in habitat util-isation between sympatric versus allopatric populationsof H turcicus This implies that two populations differnot only in the seasonal characteristics of habitat pref-erences but also in a way of habitat utilisation on a dailybasis Such differences could be the result of differentclimate and ecological characteristics between islandsbut are likely affected by the presence of another geckospecies on the island of Hvar

In summary the data presented here indicate habitatsegregation in sympatry as well as release of competitiverestraints in allopatry in the subordinate species Giventhe often complicated mechanisms of interspecies inter-actions and species co-existence (Ricklefs et al 1981Pough et al 2001 Merkle et al 2009) our data may addto a better understanding of these processes Whereasour data suggest effects of competition on habitat use in

H turcicus further studies including other componentsof the ecological niche such as diet and temperature areneeded to better understand the ecological strategies ofthis species that allow it to coexist with T mauritanica

Acknowledgements We thank all the people that participated in thefield work Many thanks to the families of Petar Zitko and TonciMaroevic for accommodation on the islands of Vis and HvarMany thanks to Pava and Simun Lisicic for their continued sup-port during the study This work was supported through grant No119-0000000-1285 of the Ministry of Science Education and Sportof the Republic of Croatia to ZT

Appendix

(See Table 5)

Table 5 Categories and subcategories of habitat used in measuring habitat utilisation forH turcicus and T mauritanica on island of Hvar(populations in sympatry) and island of Vis (H turcicus population in allopatry)

Category of habitat Sub-categoryof habitat

Description

Habitat General habitat typesWater wellField cottageField doors Specific constructions that include wooden doors two columns

and small roof above doors Intensively used by geckosWall All types of walls and stonewallsTreeColumn Power columns or field marks of column formNear to ground habitat Ground grass piles of rocks or twigs man-made debris

Position Outside Position inside or outside of shelter placeAt the entranceInside

Microhabitat Various types of microhabitat used by geckosOpen habitats Habitats that were open or offer minimal protection from

weather conditions and predatorsGroundLogStoneWallUnder stoneboardInside hole Shallow holes at open habitatsNear ceilingCeiling

Closed habitats Inside closed habitats that offers protection fromenvironmental conditions ie inside field cottage

WallBoardGroundUnder stoneboardInside holeIn crevice Crevices are defined as all types of holes deep enough that

geckos can hide from weather conditions and predatorsAnthropogenic debris Old clothes piles of twigs glasses old boxes with toolsNear ceilingceiling

Inside water well entrance Water well entrances usually used as warming spotsWallUnder panelPanel

Inside water well Very stable conditions ideal hiding places from weatherconditions

WallNear ceilingInside holeCeiling

558

References

Amat F Llorente GA Carretero MA (2003) A preliminary studyon thermal ecology activity times and microhabitat use ofLacerta agilis (Squamata Lacertidae) in the Pyrenees FoliaZool 52413ndash422

Arad Z Schwarzbaum A Werner Y (1997) Temperature selectionand thermoregulation in the Moorish gecko Tarentola mauri-tanica Amphibia Reptilia 69269ndash282

Arnold EN Ovenden D (2002) A field guide to the reptiles andamphibians of Britain and Europe 2nd edn Harper CollinsLondon

Atzori A Berti F Cencetti T Fornasiero S Tamburini M ZuffiMAL (2007) Advances in methodologies of sexing and markingless dimorphic gekkonid lizards the study case of the Moorishgecko Tarentola mauritanica Amphibia Reptilia 28449ndash454

Blouin-Demers G Bjorgan LPG Weatherhead PJ (2007) Changesin habitat use and movement patterns with body size in blackratsnakes (Elaphe obsoleta) Herpetologica 63421ndash429

Brecko J Huyghe K Vanhooydonck B Herrel A Grbac I VanDamme R (2008) Functional and ecological relevance ofintraspecific variation in body size and shape in a lizard Po-darcis melisellensis Biol J Linn Soc 94251ndash264

Brischoux F Bonnet X Shine R (2009) Determinants of dietaryspecialization a comparison of two sympatric species of seasnakes Oikos 118145ndash151

Capula M Luiselli L (1994) Tropic niche overlap in sympatricTarentola mauritanica and Hemidactylus turcicus a preliminarystudy Herpetol J 424ndash25

Carretero MA (2008) Preferred temperatures of Tarentola mauri-tanica in spring Acta Herpetol 357ndash64

Chillo V Rodrıguez D Ojeda AR (2010) Niche partitioning andcoexistence between two mammalian herbivores in the drychaco of Argentina Acta Oecol 36611ndash616

Daly BD Dickman CR Crowther MS (2007) Selection of habitatcomponents by two species of agamid lizards in sandridgedesert central Australia Austral Ecol 32825ndash833

Dangremond EM Pardini EA Knight TM (2010) Apparentcompetition with an invasive plant hastens the extinction of anendangered lupine Ecology 912261ndash2271

De PinhoWF Colli GR Vitt LJ (2009) Determinants of assemblagestructure in Neotropical dry forest lizards Aust Ecol 3497ndash115

Doughty P Shine R (1995) Life in two dimensions natural historyof the southern leaf-tailed gecko Phyllurus platurus Herpeto-logica 51193ndash201

Downes S Bauwens D (2002) An experimental demonstration ofdirect behavioural interference in two Mediterranean lacertidlizard species Anim Behav 631037ndash1046

Downes S Shine R (1998) Heat safety or solitude Using habitatselection experiments to identify a lizardrsquos priorities AnimBehav 551387ndash1396

Gill MJ Guerrero F Perez-Mellado V (1994a) Diel variation inpreferred body temperatures of the Moorish gecko Tarentolamauritanica during summer Herpetol J 456ndash59

Gill MJ Guerrero F Perez-Mellado V (1994b) Seasonal variationin diet composition and prey selection in the mediterraneangecko Tarentola mauritanica Isr J Zool 4061ndash74

Grbac I Brnin K (2006) Habitat use of sympatric populations ofPodarcis sicula and P melisellensis on a small Adriatic islandPeriod Biol 108177ndash182

Hitchcock MA McBrayer LD (2006) Thermoregulation in noc-turnal ectotherms seasonal and intraspecific variation in theMediterranean Gecko (Hemidactylus turcicus) J Herpetol40185ndash195

Hodar JA Pleguezuelos JM Villafranca C Frenandes-CardeneteJR (2006) Foraging mode of the Moorish gecko Tarentolamauritanica in an arid environment inferences from abioticsetting prey availability and dietary composition J AridEnviron 6583ndash93

Table 5 continued

Category of habitat Sub-categoryof habitat

Description

SubstrateOld clothPaperConcreteStone-concreteStoneWoodBrickPlastic glassMetalTileDirt grass

Type of behaviorStillStillactive Geckos found standing still outside the typical hiding places

ie on wall inside field cottage during cold dayActiveEatingWarmingStillwarming Inactive non-moving geckos that chose warming positions ie

inside water well entrance during winter monthsSun bathing

Cardinal directionNone Geckos found in the middle of field cottage or water well had

no general cardinal directionNorthEastWestSouth

559

Honkavaara J Dunn DW Ilvonen S Suhonen J (2011) Sympatricshift in a male sexual ornament in the damselfly Calopteryxsplendens J Evol Biol 24139ndash145 doi101111j1420-9101201002146x

Huey RB Pianka ER (1977) Patterns of niche overlap amongbroadly sympatric versus narrowly sympatric Kalahari lizards(Scincidae Mabuya) Ecology 5819ndash28

Hunt JFG Bonsall MB (2009) The effects of colonization extinc-tion and competition on co-existence in metacommunitiesJ Anim Ecol 78866ndash879

Johnson J McBrayer LD Saenz D (2005) Allometry sexual sizedimorphism and niche partitioning in the Mediterranean gecko(Hemidactylus turcicus) Southwest Nat 50435ndash439 doi1018940038-4909(2005)050[0435ASSDAN]20CO2

Kirschel ANG Blumstein DT Smith TB (2009) Character dis-placement of song and morphology in African tinkerbirds ProcNatl Acad Sci USA 1068256ndash8261

Kjoss V Litvaitis J (2001) Community structure of snakes in ahuman-dominated landscape Biol Conserv 98285ndash292

Kumstatova T Brinke T Tomkova S Fuchs R Petrusek A (2004)Habitat preferences of tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric and allopatric localitiesJ Ornithol 145334ndash342 doi101007s10336-004-0048-3

Lima A Moreira G (1993) Effects of prey size and foraging modeon the ontogenetic change in feeding niche of Colostethusstephani (Anura Dendrobatidae) Oecologia 9593ndash120

Locey KJ Stone PA (2006) Factors affecting range expansion inthe introduced Mediterranean gecko Hemidactylus turcicusJ Herpetol 40526ndash530

Luh HK Pimm SL (1993) The assembly of ecological communitiesa minimalist approach J Anim Ecol 62749ndash765

Luiselli L (2006) Resource partitioning and interspecific competi-tion in snakes the search for general geographical and guildpatterns Oikos 114193ndash211

Luiselli L Capizzi D (1999) Ecological distribution of the geckosTarentola mauritanica and Hemidactylus turcicus in the urbanarea of Rome in relation to age of buildings and condition ofthe walls J Herpetol 33316ndash319

Marquet PA Bozinovic F Medel RG Werner YL Jaksic FM(1990) Ecology of Garthia gaudichaudi a gecko endemic to thesemiarid region of Chile J Herpetol 24431ndash434

McGrath CC Lewis WM Jr (2007) Competition and predation asmechanisms for displacement of Greenback Cutthroat Trout byBrook Trout Trans Am Fish Soc 1361381ndash1392

Merkle JA Stahler DR Smith DW (2009) Interference competitionbetween gray wolves and coyotes in Yellowstone NationalPark Can J Zool 8756ndash63

Museth J Borgstroslashm R Brittain JE (2010) Diet overlap betweenintroduced European minnow (Phoxinus phoxinus) and youngbrown trout (Salmo trutta) in the lake Oslashvre Heimdalsvatn aresult of abundantresources or forced niche overlap Hydrobi-ologia 64293ndash100 doi101007s10750-010-0162-6

Nemes S Vogrin M Hartel T Ollerer K (2006) Habitat selection atthe sand lizard (Lacerta agilis) ontogenetic shifts N West JZool 217ndash26

Pianka ER (1969) Sympatry of desert lizards (Ctenotus) in WesternAustralia Ecology 501012ndash1030

Pianka ER (1974) Niche overlap and diffuse competition ProcNatl Acad Sci USA 712141ndash2145

Pianka ER Huey RB (1978) Comparative ecology resource util-isation and niche segregation among gekkonid lizards in theSouthern Kalahari Copeia 4691ndash701

Pough FH Andrews RM Cadle JE Crump ML Savitzky AHWells KD (2001) Herpetology 2nd edn Prentice-Hall Engle-wood Cliffs NJ

Punzo F (2001) The Mediterranean gecko Hemidactylus turcicuslife in an urban landscape Fla Sci 6456ndash66

Reinert HK (1984) Habitat variation within sympatric snakepopulations Ecology 651673ndash1682

Rice AM Leichty AR Pfennig DW (2009) Parallel evolution andecological selection replicated character displacement inspadefoot toads Proc R Soc B 2764189ndash4196 doi101098rspb20091337

Ricklefs RE Cochran D Pianka ER (1981) A morphologicalanalysis of the structure of communities of lizards in deserthabitats Ecology 621474ndash1483

Schoener TW (1974a) The compression hypothesis and temporalresource partitioning Proc Natl Acad Sci USA 714169ndash4172

Schoener TW (1974b) Resource partitioning in ecological com-munities Science 18527ndash39

Schoener TW (1975) Presence and absence of habitat shift in somewidespread lizard species Ecol Monogr 45233ndash258

Schoener TW (1983) Field experiments on interspecific competi-tion Am Nat 122240ndash285

Schoener TW Losos JB Spiller DA (2005) Island biogeography ofpopulations an introduced species transform survival patternsScience 3101807ndash1809 doi101126science1120165

Selcer KW (1986) Life history of a successful colonizer the Med-iterranean gecko Hemidactylus turcicus in Southern TexasCopeia 4956ndash962

Torok J Toth L (1999) Asymmetric competition between two titspecies a reciprocial removal experiment J Anim Ecol68338ndash345

Vitt LJ Zani PA (1998) Prey use among sympatric lizard species inlowland rain forest of Nicaragua J Trop Ecol 14537ndash559

Werner YL Takahashi H Mautz WJ Ota H (2005) Behavior ofthe terrestrial nocturnal lizards Goniurosaurus kuroiwae ku-roiwae and Eublepharis macularius (Reptilia Eublepharidae) ina thigmothermal gradient J Ther Biol 30247ndash254 doi101016jjtherbio200412004

Yamauchi A Miki T (2009) Intraspecific niche flexibility facilitatesspecies coexistence in a competitive community with a fluctu-ating environment Oikos 11855ndash66

560

References

Amat F Llorente GA Carretero MA (2003) A preliminary studyon thermal ecology activity times and microhabitat use ofLacerta agilis (Squamata Lacertidae) in the Pyrenees FoliaZool 52413ndash422

Arad Z Schwarzbaum A Werner Y (1997) Temperature selectionand thermoregulation in the Moorish gecko Tarentola mauri-tanica Amphibia Reptilia 69269ndash282

Arnold EN Ovenden D (2002) A field guide to the reptiles andamphibians of Britain and Europe 2nd edn Harper CollinsLondon

Atzori A Berti F Cencetti T Fornasiero S Tamburini M ZuffiMAL (2007) Advances in methodologies of sexing and markingless dimorphic gekkonid lizards the study case of the Moorishgecko Tarentola mauritanica Amphibia Reptilia 28449ndash454

Blouin-Demers G Bjorgan LPG Weatherhead PJ (2007) Changesin habitat use and movement patterns with body size in blackratsnakes (Elaphe obsoleta) Herpetologica 63421ndash429

Brecko J Huyghe K Vanhooydonck B Herrel A Grbac I VanDamme R (2008) Functional and ecological relevance ofintraspecific variation in body size and shape in a lizard Po-darcis melisellensis Biol J Linn Soc 94251ndash264

Brischoux F Bonnet X Shine R (2009) Determinants of dietaryspecialization a comparison of two sympatric species of seasnakes Oikos 118145ndash151

Capula M Luiselli L (1994) Tropic niche overlap in sympatricTarentola mauritanica and Hemidactylus turcicus a preliminarystudy Herpetol J 424ndash25

Carretero MA (2008) Preferred temperatures of Tarentola mauri-tanica in spring Acta Herpetol 357ndash64

Chillo V Rodrıguez D Ojeda AR (2010) Niche partitioning andcoexistence between two mammalian herbivores in the drychaco of Argentina Acta Oecol 36611ndash616

Daly BD Dickman CR Crowther MS (2007) Selection of habitatcomponents by two species of agamid lizards in sandridgedesert central Australia Austral Ecol 32825ndash833

Dangremond EM Pardini EA Knight TM (2010) Apparentcompetition with an invasive plant hastens the extinction of anendangered lupine Ecology 912261ndash2271

De PinhoWF Colli GR Vitt LJ (2009) Determinants of assemblagestructure in Neotropical dry forest lizards Aust Ecol 3497ndash115

Doughty P Shine R (1995) Life in two dimensions natural historyof the southern leaf-tailed gecko Phyllurus platurus Herpeto-logica 51193ndash201

Downes S Bauwens D (2002) An experimental demonstration ofdirect behavioural interference in two Mediterranean lacertidlizard species Anim Behav 631037ndash1046

Downes S Shine R (1998) Heat safety or solitude Using habitatselection experiments to identify a lizardrsquos priorities AnimBehav 551387ndash1396

Gill MJ Guerrero F Perez-Mellado V (1994a) Diel variation inpreferred body temperatures of the Moorish gecko Tarentolamauritanica during summer Herpetol J 456ndash59

Gill MJ Guerrero F Perez-Mellado V (1994b) Seasonal variationin diet composition and prey selection in the mediterraneangecko Tarentola mauritanica Isr J Zool 4061ndash74

Grbac I Brnin K (2006) Habitat use of sympatric populations ofPodarcis sicula and P melisellensis on a small Adriatic islandPeriod Biol 108177ndash182

Hitchcock MA McBrayer LD (2006) Thermoregulation in noc-turnal ectotherms seasonal and intraspecific variation in theMediterranean Gecko (Hemidactylus turcicus) J Herpetol40185ndash195

Hodar JA Pleguezuelos JM Villafranca C Frenandes-CardeneteJR (2006) Foraging mode of the Moorish gecko Tarentolamauritanica in an arid environment inferences from abioticsetting prey availability and dietary composition J AridEnviron 6583ndash93

Table 5 continued

Category of habitat Sub-categoryof habitat

Description

SubstrateOld clothPaperConcreteStone-concreteStoneWoodBrickPlastic glassMetalTileDirt grass

Type of behaviorStillStillactive Geckos found standing still outside the typical hiding places

ie on wall inside field cottage during cold dayActiveEatingWarmingStillwarming Inactive non-moving geckos that chose warming positions ie

inside water well entrance during winter monthsSun bathing

Cardinal directionNone Geckos found in the middle of field cottage or water well had

no general cardinal directionNorthEastWestSouth

559

Honkavaara J Dunn DW Ilvonen S Suhonen J (2011) Sympatricshift in a male sexual ornament in the damselfly Calopteryxsplendens J Evol Biol 24139ndash145 doi101111j1420-9101201002146x

Huey RB Pianka ER (1977) Patterns of niche overlap amongbroadly sympatric versus narrowly sympatric Kalahari lizards(Scincidae Mabuya) Ecology 5819ndash28

Hunt JFG Bonsall MB (2009) The effects of colonization extinc-tion and competition on co-existence in metacommunitiesJ Anim Ecol 78866ndash879

Johnson J McBrayer LD Saenz D (2005) Allometry sexual sizedimorphism and niche partitioning in the Mediterranean gecko(Hemidactylus turcicus) Southwest Nat 50435ndash439 doi1018940038-4909(2005)050[0435ASSDAN]20CO2

Kirschel ANG Blumstein DT Smith TB (2009) Character dis-placement of song and morphology in African tinkerbirds ProcNatl Acad Sci USA 1068256ndash8261

Kjoss V Litvaitis J (2001) Community structure of snakes in ahuman-dominated landscape Biol Conserv 98285ndash292

Kumstatova T Brinke T Tomkova S Fuchs R Petrusek A (2004)Habitat preferences of tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric and allopatric localitiesJ Ornithol 145334ndash342 doi101007s10336-004-0048-3

Lima A Moreira G (1993) Effects of prey size and foraging modeon the ontogenetic change in feeding niche of Colostethusstephani (Anura Dendrobatidae) Oecologia 9593ndash120

Locey KJ Stone PA (2006) Factors affecting range expansion inthe introduced Mediterranean gecko Hemidactylus turcicusJ Herpetol 40526ndash530

Luh HK Pimm SL (1993) The assembly of ecological communitiesa minimalist approach J Anim Ecol 62749ndash765

Luiselli L (2006) Resource partitioning and interspecific competi-tion in snakes the search for general geographical and guildpatterns Oikos 114193ndash211

Luiselli L Capizzi D (1999) Ecological distribution of the geckosTarentola mauritanica and Hemidactylus turcicus in the urbanarea of Rome in relation to age of buildings and condition ofthe walls J Herpetol 33316ndash319

Marquet PA Bozinovic F Medel RG Werner YL Jaksic FM(1990) Ecology of Garthia gaudichaudi a gecko endemic to thesemiarid region of Chile J Herpetol 24431ndash434

McGrath CC Lewis WM Jr (2007) Competition and predation asmechanisms for displacement of Greenback Cutthroat Trout byBrook Trout Trans Am Fish Soc 1361381ndash1392

Merkle JA Stahler DR Smith DW (2009) Interference competitionbetween gray wolves and coyotes in Yellowstone NationalPark Can J Zool 8756ndash63

Museth J Borgstroslashm R Brittain JE (2010) Diet overlap betweenintroduced European minnow (Phoxinus phoxinus) and youngbrown trout (Salmo trutta) in the lake Oslashvre Heimdalsvatn aresult of abundantresources or forced niche overlap Hydrobi-ologia 64293ndash100 doi101007s10750-010-0162-6

Nemes S Vogrin M Hartel T Ollerer K (2006) Habitat selection atthe sand lizard (Lacerta agilis) ontogenetic shifts N West JZool 217ndash26

Pianka ER (1969) Sympatry of desert lizards (Ctenotus) in WesternAustralia Ecology 501012ndash1030

Pianka ER (1974) Niche overlap and diffuse competition ProcNatl Acad Sci USA 712141ndash2145

Pianka ER Huey RB (1978) Comparative ecology resource util-isation and niche segregation among gekkonid lizards in theSouthern Kalahari Copeia 4691ndash701

Pough FH Andrews RM Cadle JE Crump ML Savitzky AHWells KD (2001) Herpetology 2nd edn Prentice-Hall Engle-wood Cliffs NJ

Punzo F (2001) The Mediterranean gecko Hemidactylus turcicuslife in an urban landscape Fla Sci 6456ndash66

Reinert HK (1984) Habitat variation within sympatric snakepopulations Ecology 651673ndash1682

Rice AM Leichty AR Pfennig DW (2009) Parallel evolution andecological selection replicated character displacement inspadefoot toads Proc R Soc B 2764189ndash4196 doi101098rspb20091337

Ricklefs RE Cochran D Pianka ER (1981) A morphologicalanalysis of the structure of communities of lizards in deserthabitats Ecology 621474ndash1483

Schoener TW (1974a) The compression hypothesis and temporalresource partitioning Proc Natl Acad Sci USA 714169ndash4172

Schoener TW (1974b) Resource partitioning in ecological com-munities Science 18527ndash39

Schoener TW (1975) Presence and absence of habitat shift in somewidespread lizard species Ecol Monogr 45233ndash258

Schoener TW (1983) Field experiments on interspecific competi-tion Am Nat 122240ndash285

Schoener TW Losos JB Spiller DA (2005) Island biogeography ofpopulations an introduced species transform survival patternsScience 3101807ndash1809 doi101126science1120165

Selcer KW (1986) Life history of a successful colonizer the Med-iterranean gecko Hemidactylus turcicus in Southern TexasCopeia 4956ndash962

Torok J Toth L (1999) Asymmetric competition between two titspecies a reciprocial removal experiment J Anim Ecol68338ndash345

Vitt LJ Zani PA (1998) Prey use among sympatric lizard species inlowland rain forest of Nicaragua J Trop Ecol 14537ndash559

Werner YL Takahashi H Mautz WJ Ota H (2005) Behavior ofthe terrestrial nocturnal lizards Goniurosaurus kuroiwae ku-roiwae and Eublepharis macularius (Reptilia Eublepharidae) ina thigmothermal gradient J Ther Biol 30247ndash254 doi101016jjtherbio200412004

Yamauchi A Miki T (2009) Intraspecific niche flexibility facilitatesspecies coexistence in a competitive community with a fluctu-ating environment Oikos 11855ndash66

560

Honkavaara J Dunn DW Ilvonen S Suhonen J (2011) Sympatricshift in a male sexual ornament in the damselfly Calopteryxsplendens J Evol Biol 24139ndash145 doi101111j1420-9101201002146x

Huey RB Pianka ER (1977) Patterns of niche overlap amongbroadly sympatric versus narrowly sympatric Kalahari lizards(Scincidae Mabuya) Ecology 5819ndash28

Hunt JFG Bonsall MB (2009) The effects of colonization extinc-tion and competition on co-existence in metacommunitiesJ Anim Ecol 78866ndash879

Johnson J McBrayer LD Saenz D (2005) Allometry sexual sizedimorphism and niche partitioning in the Mediterranean gecko(Hemidactylus turcicus) Southwest Nat 50435ndash439 doi1018940038-4909(2005)050[0435ASSDAN]20CO2

Kirschel ANG Blumstein DT Smith TB (2009) Character dis-placement of song and morphology in African tinkerbirds ProcNatl Acad Sci USA 1068256ndash8261

Kjoss V Litvaitis J (2001) Community structure of snakes in ahuman-dominated landscape Biol Conserv 98285ndash292

Kumstatova T Brinke T Tomkova S Fuchs R Petrusek A (2004)Habitat preferences of tree pipit (Anthus trivialis) and meadowpipit (A pratensis) at sympatric and allopatric localitiesJ Ornithol 145334ndash342 doi101007s10336-004-0048-3

Lima A Moreira G (1993) Effects of prey size and foraging modeon the ontogenetic change in feeding niche of Colostethusstephani (Anura Dendrobatidae) Oecologia 9593ndash120

Locey KJ Stone PA (2006) Factors affecting range expansion inthe introduced Mediterranean gecko Hemidactylus turcicusJ Herpetol 40526ndash530

Luh HK Pimm SL (1993) The assembly of ecological communitiesa minimalist approach J Anim Ecol 62749ndash765

Luiselli L (2006) Resource partitioning and interspecific competi-tion in snakes the search for general geographical and guildpatterns Oikos 114193ndash211

Luiselli L Capizzi D (1999) Ecological distribution of the geckosTarentola mauritanica and Hemidactylus turcicus in the urbanarea of Rome in relation to age of buildings and condition ofthe walls J Herpetol 33316ndash319

Marquet PA Bozinovic F Medel RG Werner YL Jaksic FM(1990) Ecology of Garthia gaudichaudi a gecko endemic to thesemiarid region of Chile J Herpetol 24431ndash434

McGrath CC Lewis WM Jr (2007) Competition and predation asmechanisms for displacement of Greenback Cutthroat Trout byBrook Trout Trans Am Fish Soc 1361381ndash1392

Merkle JA Stahler DR Smith DW (2009) Interference competitionbetween gray wolves and coyotes in Yellowstone NationalPark Can J Zool 8756ndash63

Museth J Borgstroslashm R Brittain JE (2010) Diet overlap betweenintroduced European minnow (Phoxinus phoxinus) and youngbrown trout (Salmo trutta) in the lake Oslashvre Heimdalsvatn aresult of abundantresources or forced niche overlap Hydrobi-ologia 64293ndash100 doi101007s10750-010-0162-6

Nemes S Vogrin M Hartel T Ollerer K (2006) Habitat selection atthe sand lizard (Lacerta agilis) ontogenetic shifts N West JZool 217ndash26

Pianka ER (1969) Sympatry of desert lizards (Ctenotus) in WesternAustralia Ecology 501012ndash1030

Pianka ER (1974) Niche overlap and diffuse competition ProcNatl Acad Sci USA 712141ndash2145

Pianka ER Huey RB (1978) Comparative ecology resource util-isation and niche segregation among gekkonid lizards in theSouthern Kalahari Copeia 4691ndash701

Pough FH Andrews RM Cadle JE Crump ML Savitzky AHWells KD (2001) Herpetology 2nd edn Prentice-Hall Engle-wood Cliffs NJ

Punzo F (2001) The Mediterranean gecko Hemidactylus turcicuslife in an urban landscape Fla Sci 6456ndash66

Reinert HK (1984) Habitat variation within sympatric snakepopulations Ecology 651673ndash1682

Rice AM Leichty AR Pfennig DW (2009) Parallel evolution andecological selection replicated character displacement inspadefoot toads Proc R Soc B 2764189ndash4196 doi101098rspb20091337

Ricklefs RE Cochran D Pianka ER (1981) A morphologicalanalysis of the structure of communities of lizards in deserthabitats Ecology 621474ndash1483

Schoener TW (1974a) The compression hypothesis and temporalresource partitioning Proc Natl Acad Sci USA 714169ndash4172

Schoener TW (1974b) Resource partitioning in ecological com-munities Science 18527ndash39

Schoener TW (1975) Presence and absence of habitat shift in somewidespread lizard species Ecol Monogr 45233ndash258

Schoener TW (1983) Field experiments on interspecific competi-tion Am Nat 122240ndash285

Schoener TW Losos JB Spiller DA (2005) Island biogeography ofpopulations an introduced species transform survival patternsScience 3101807ndash1809 doi101126science1120165

Selcer KW (1986) Life history of a successful colonizer the Med-iterranean gecko Hemidactylus turcicus in Southern TexasCopeia 4956ndash962

Torok J Toth L (1999) Asymmetric competition between two titspecies a reciprocial removal experiment J Anim Ecol68338ndash345

Vitt LJ Zani PA (1998) Prey use among sympatric lizard species inlowland rain forest of Nicaragua J Trop Ecol 14537ndash559

Werner YL Takahashi H Mautz WJ Ota H (2005) Behavior ofthe terrestrial nocturnal lizards Goniurosaurus kuroiwae ku-roiwae and Eublepharis macularius (Reptilia Eublepharidae) ina thigmothermal gradient J Ther Biol 30247ndash254 doi101016jjtherbio200412004

Yamauchi A Miki T (2009) Intraspecific niche flexibility facilitatesspecies coexistence in a competitive community with a fluctu-ating environment Oikos 11855ndash66

560