Differences in sexual dimorphism among four gazelle taxa (Gazella spp.) in the Middle East

copy Koninklijke Brill NV Leiden 2010 DOI 101163157075610X523279

Animal Biology 60 (2010) 395ndash412 brillnlab

Diff erences in sexual dimorphism among four gazelle taxa ( Gazella spp) in the Middle East

Torsten Wronski 12 Mohamed A Sandouka 12 Martin Plath 3 and Peter Cunningham 12

1 Conservation Programmes Zoological Society of London Regentrsquos Park London NW1 4RY United Kingdom

2 King Khalid Wildlife Research Centre National Commission for Wildlife Conservation and Development PO Box 61681 Riyadh 11575 Kingdom of Saudi Arabia

3 University of Frankfurt Department of Ecology and Evolution FrankfurtM Germany

Abstract Sexual selection can lead to sexual dimorphism where elaborated traits used in mate attraction or weap-onry are more expressed in the male sex Th e degree of sexual dimorphism however is known to vary even among closely related taxa Here we examined sexual dimorphism in horn length and three measures related to body size (body weight shoulder height and neck circumference) in four gazelle taxa represent-ing at least three species ie Dorcas gazelle ( G dorcas ) Sand gazelle ( G subgutturosa marica ) and Mountain gazelle ( G gazella ) Th e latter is represented by two distinctive phenotypes maintained and bred at the King Khalid Wildlife Research Centre in Saudi Arabia We describe marked diff erences in sexual dimor-phism among taxa For example the diff erence in sexually dimorphic horn development was driven pri-marily by females exhibiting pronounced diff erences in horn development We discuss how divergent mating systems and group sizes aff ect these diff erences among the examined taxa with more competition in larger groups probably promoting the evolution of larger horns in females thereby leading to less sexual dimorphism copy Koninklijke Brill NV Leiden 2010

Keywords Gazelles Arabian Peninsula sexual selection male-male competition captive breeding

Introduction

Predicting the variation in the intensity of sexual and natural selection across species is a key challenge to evolutionary ecologists (Andersson 1994 Shuster and Wade 2003 Tobler et al 2008 ) Sexual selectionmdasheither in the form of intra-sexual selection

) Corresponding authors email t_wronskigmxde Martin_Plathwebde

396 T Wronski et al Animal Biology 60 (2010) 395ndash412

through male competition for mates or in the form of intra-sexual selection via female choicemdashoften leads to the elaboration of male secondary sexual traits (causing sexual dimorphism Packer 1983 Andersson 1994 Loison et al 1999 Abraham 1998 Karino and Haijima 2001 Peacuterez-Barberia et al 2002 Isaac 2005 ) while natural selection can counteract this process (eg Ryan 1985 Zuk and Kolluru 1998 Zuk et al 2006 ) In the present study we make a fi rst attempt to study sexual selection in four gazelle taxaphenotypes ( Gazella spp) from the Middle East by investigating sexual dimorphism in several morphological traits (most importantly horn length) Th is study is intended as a starting point for future investigations comparing other (behavioural) aspects of sexual selection in some of the little investigated taxa included in this study like male mating tactics and aggressive behaviour and female mate choice

Sexual dimorphism in bovids horned males and hornless females

In most bovid species sexual dimorphism in size and shape of horns and body propor-tions is striking for example in many species females are hornless while males often have sophisticated weaponry (Ansell 1971 Jarman 1974 Estes 1974 ) Th is can be attributed to the fact that males compete for mating opportunities (Walther 1961 Geist 1966 Janis 1982 Jarman 1983 ) and thus horn size and structure can be pre-dictive of mating success (Clutton-Brock et al 1980 Popp 1985 Bro-Joslashrgensen 2007 ) Darwin ( 1871 ) was one of the fi rst to develop the hypothesis that sexual selec-tion is a major force driving the evolution of weaponry in bovid males He believed that male horns were selected primarily through their role in intra-sexual combat Following this line of interpretation female hornlessness in some bovid species would be due to natural selection countering the expression of weaponry eg because horns are energetically costly and or hamper an individualrsquos ability to escape from predators (Roberts 1996 ) Indeed smaller species (lt 25 kg) that rely on crypsis to avoid preda-tors typically have hornless females (Packer 1983 )

Other authors have highlighted the potential role of natural selection for the evolu-tion of bovid horns Indeed some species can use their horns in defence against carni-vore predators (Kruuk 1972 Pienaar 1969 ) and this function has been proposed as one potential explanation for the development of horned females in some species (Packer 1983 )

Estes ( 1991a ) suggested that the primary function of female hornsmdashwhere existentmdashis to mimic those of their adolescent male off spring (andromimicry) which is thought to prevent adult males in the group from chasing their male off spring away from the group herd On the other hand Geist ( 1977 ) and Janis ( 1982 ) argued that female horns function as weapons to reduce feeding competition with males Another formulation of that hypothesis states that female horns may discourage unwanted sex-ual harassment by sub-adult males (Geist 1974a b) Finally Roberts ( 1996 ) suggested that females may develop horns as weapons during competition for limiting resources (female competition hypothesis)

T Wronski et al Animal Biology 60 (2010) 395ndash412 397

Diff erences in sexual dimorphism among bovid species

In a recent review it was shown that male horn length depends on factors that aff ect the potential number of females a male could monopolize and thus is correlated positively with group size and negatively with male territoriality (Bro-Joslashrgensen 2007 ) Sexual body size dimorphism also correlates positively with group size and negatively with territoriality (Bro-Joslashrgensen 2007 ) In contrast female horn length appears not to be aff ected by factors related to the mating system suggesting that this trait is mainly under natural selection (Roberts 1996 ) In our study general information on the mat-ing systems was available for all taxa included and is viewed in light of the above-mentioned hypotheses

Several studies have investigated sexual dimorphism in African bovids inhabiting both open savannahs or deserts and forest habitats (Jarman 1974 1983 Packer 1983 Estes 1991b ) and several comparative reviews on sexual dimorphism in ungulates are now available (Janis 1982 Packer 1983 Roberts 1996 Weckerly 1998 Loison et al 1999 Peacuterez-Barberia et al 2002 Caro et al 2003 Bro-Joslashrgensen 2007 ) However a comparative analysis of sexual dimorphism in gazelles ( Gazella spp) has not yet been conducted although the genus was included in the reviews by Weckerly ( 1998 ) Loison et al ( 1999 ) and Bro-Joslashrgensen ( 2007 ) In the present study we compare two diff erent phenotypes of Mountain gazelle ( Gazella gazella lsquophenotype Arsquo lsquophenotype Brsquo) Dorcas gazelle ( G dorcas ) and Sand gazelle ( G subgutturosa marica ) all inhabiting arid to hyper-arid areas on the Arabian Peninsula or the Levant We investigated patterns of sexual dimorphism in horn length and general body size (shoulder height body weight and neck circumference) Diff erences in the sex-specifi c expression of those traits among taxa are discussed in the light of the existing literature and the interesting fact that the degree of dimorphism varies within as well as between gazelle species is highlighted

Material and methods

Study species

Animal maintenance All animals included in this study stemmed from a captive breeding programme at the King Khalid Wildlife Research Centre (KKWRC) in Th umamah Saudi Arabia (see Kichenside and Lindsay 1997 Kichenside 1998 for routine maintenance conditions) Gazelles were maintained in 100 acute 50 m outdoor enclosures with a minimum fence height of 2 m Breeding-group size was 10 animals per enclosure with a male female stocking rate of 1 9 Dietary requirements of gazelles were met by providing fresh and dry (baled) alfalfa (1-15 kg per gazelle per day) and a concentrate prepared specifi cally for gazelles (250-300 g per adult gazelle per day) With the exception of an iodized salt block no other additives were given Data from Gazella gazella (lsquophenotype Arsquo) and Gazella subgutturosa marica were reanalysed from previous studies describing the general growth patterns of those two species for


estimating age under fi eld conditions [Wronski and Sandoka (2008) and Cunningham and Sandoka (submitted) respectively]

Gazella gazella lsquophenotype Arsquo ( fi g 1a ) Mountain gazelle included in this study originated from diff erent parts of Saudi Arabia and may therefore represent diff erent subspecies or even intra-specifi c hybrids (Hammond et al 2000 ) Th e species inhabits a wide range of habitats but prefer rocky hilly terrain with moderate vegetation (Baharav 1981 1983 ) while avoiding open sand plains and dense forest (Mendelsohn et al 1995) Mountain gazelle are described as intermittent grazers (Baharav 1981 1983 Harrison and Bates 1991 ) but their distribution on the Arabian Peninsula closely coincides with that of Acacia spp (Vesey-Fitzgerald 1952 Mendelssohn et al 1997 ) Although they feed on a wide range of plants (Mendelsohn et al 1995 Habibi 1991 ) recent studies have shown that Acacia spp indeed represents a major food plant of Mountain gazelles (Campbell 1997 Robertson 1995 T Wronski unpubl data) Th e species is sedentary and not dependent on surface water but is less tolerant to thirst than Dorcas or Sand gazelles (Mendelsohn et al 1995) Th ey are best adapted to a rainfall regime of 300ndash400 mm and average temperatures between 21ndash23˚C and can withstand temperatures up to 45˚C but also frost (Mendelsohn et al 1995) Females live in small to medium-sized groups (2 to 16 individuals) based on a matrilinear organisation (Mendelssohn and Yom-Tov 1987 Dunham 1999 ) and inhabit home ranges of 02ndash46 km 2 (Mendelsohn et al 1995 Dunham 1998 Wronski submitted) Adult males either occupy permanent territories (02ndash05 km 2 ) or join sub-adult and young-adult males in bachelor groups (Mendelsohn et al 1995) Mountain gazelles breed throughout the year but breeding peaks occur in spring and fall (Harrison 1968 Habibi 1991 1992 Mendelsohn et al 1995)

Gazella gazella lsquophenotype Brsquo ( fi g 1b ) Although lsquophenotype Brsquo animals are genetically much closer to G gazella lsquophenotype Arsquo than for example to G gazella from the Golan Heights in SyriaIsrael (Wronski et al 2010 ) they represent a paradox in that they are physically very distinctive from lsquophenotype Arsquo lsquoPhenotype Brsquo gazelles are distinctively smaller than other G gazella dark grey to black in colour with brown-orange legs a thick fur and with a comparatively placid temperament Classifi cation has drifted from initially G g muscatensis through G bilkis to G g erlangeri and G erlangeri (Greth and Williamson 1996 Groves 1996 Groves 1997 ) Current genetic analyses indicate that they form a very uniform clade within G gazella indicating a phylogenetic affi liation with animals from the eastern part of the Arabian Peninsula (Hammond et al 2000 Wronski et al 2010 ) Th is taxon is best described as a phenotypically well defi ned but only narrowly genetically diff erentiated subspecies of Mountain gazelle No information is available on the habitat requirements and ecology of this distinctive phenotype and the exact provenance of these gazelles remains obscure Th e gazelles were confi scated from animal traders in Jeddah and Najran (south-western Saudi Arabia) in 1994 or were given in 1996 to KKWRC for husbandry and breeding by the Prince of Taif (Saudi Arabia)


Gazella dorcas ( fi g1c ) Th e Dorcas gazelle ( Gazella dorcas ) occurs in Ethiopia and Sudan east of the Nile in Egypt and southern Israel (Groves 1981 ) Th e species inhabits savannahs semi-arid desert plains and broad wadis but avoids hilly terrain (Yom-Tov et al 1995 ) Like Mountain gazelle they are closely associated with Acacia spp which is their major food plant (Yom-Tov et al 1995 Baharav 1980 1982 1985 ) Dorcas gazelle are the least dependent on surface water (Carlisle and Ghobrial 1968 Kingswood and Blank 1996 ) of the species included in this study and are thus best adapted to hyper-arid desert conditions In their natural habitat they face extreme desert conditions where ambient temperatures may reach 55˚C (Ghobrial 1974 ) and average rainfall is below 25 mm often with large annual fl uctuations (Yom-Tov and Ilani 1987 ) In rich habitats male Dorcas gazelles occupy territories year-round but in areas of poor food availability they form harems or occupy territories only during the mating season (Essghaier and Jones 1981) During periods with suffi cient rain and food the animals are widely scattered while during dry periods they are clumped in large numbers in wadis where moisture persists (up to 100 individuals per group Ghobrial 1974 Hufnagel 1972 ) Female herds usually consist of 2 to 12 individuals bachelor groups reach 2 to 5 males (Baharav 1980 Hufnagel 1972 )

Th e Dorcas gazelles examined at KKWRC are reported to be of Sudanese origin and were presented as gifts to King Khalid in the 1970rsquos

Figure 1 Male and female of four gazelle taxa (a) Gazella gazella lsquophenotype Arsquo (b) lsquo Gazella gazella lsquophenotype Brsquo (c) Gazella dorcas and (d) Gazella subgutturosa marica inhabiting the Middle East Th is fi gure is published in colour online see httpwwwbrillnlab


Gazella subgutturosa marica ( fi g 1d ) Sand gazelle ( Gazella subgutturosa marica ) inhabit open sand and gravel plains on the Arabian Peninsula nearly devoid of vegetation (Morrison-Scott 1939 Th ouless et al 1991 ) Th ey are predominantly grazers but take browse when grazing conditions are poor (Mohammed et al 1991 Harrison and Bates 1991 Th oughless et al 1991) Like Dorcas gazelles they are well adapted to hyper-arid desert conditions and their heat resilience can withstand body temperatures up to 425˚C (Williamson 1992) Sand gazelles migrate considerable distances following rain and searching for green pasture (Legge and Rowley-Conwy 1987 Mendelssohn 1974 ) After rainfall the species becomes highly gregarious and group size can reach several hundred individuals (Allen 1940 Mendelssohn 1974 ) while during the dry season female groups are loose and number between 10 and 30 individuals ( Jamsheed 1976 ) Only during the rut (ie from September to November Habibi et al 1993 ) adult males occupy small territories but are otherwise either solitary or organised in large bachelor groups (Habibi et al 1993 ) During courtship males have swollen necks and their preorbital glands are dilated and exude a tarry secretion (Allen 1940 Habibi et al 1993 )

Sand gazelles at KKWRC originated from diff erent parts of the Arabian Peninsula Characteristic for this subspecies is the possession of horns in females in contrast to the subspecies inhabiting the central Asian steppes between Iraq and Mongolia (Kingswood and Blank 1996 )

Morphological measurements

Data collection Data from 133 Mountain gazelles (lsquophenotype Arsquo 39 males 94 females) 24 Dorcas gazelles (8 males 16 females) 27 G gazella lsquophenotype Brsquo (20 males 7 females) and 379 Sand gazelles (150 males 229 females) of known age (all born at KKWRC) were recorded during the routine annual vaccination programme at KKWRC between 27 th February and 21 st June 2008 Th e following information was recorded from living animals sex horn length (measured from horn base to horn tip following the lyrate shape of the horn) shoulder height body weight and neck circumference Male gazelles are not only heavier but also taller than females Moreover the neck in male gazelles is generally thicker than that of females particularly in Sand gazelles were it swells considerably during the rut (Kingswood and Blank 1996 Habibi 1991 Habibi et al 1993 ) Shoulder height and neck circumference were therefore included in our analysis of sexual dimorphism Th e age of all measured individuals was obtained from the KKWRC Animal Records Keeping System (ARKS4)-database (software used for institutional animal record keeping ISIS SPARKSstudbook support)

Statistical analysis We ran a multivariate general linear model (GLM) using SPSS 120 in which all measured variables (see above) were included as dependent variables whereas lsquosexrsquo and lsquospeciesrsquo were included as factors and lsquoagersquo as a covariate Interactions were removed from the model if non-signifi cant starting with the highest-level interaction(s) We were particularly interested to examine interaction eff ects among the independent variables eg an interaction eff ect of lsquospecies by sexrsquo would indicate


Hor

n le

ngth

(cm

)

Age (years)

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0

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10

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25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Ggazella lsquophenotype Arsquo

G gazella lsquophenotype Brsquo

G dorcas

G s marica

Figure 2 Sexual dimorphism in horn length of four gazelle taxa ( Gazella gazella lsquophenotype Arsquo Gazella dorcas lsquo Gazella gazella lsquophenotype Brsquo Gazella subgutturosa marica ) inhabiting the Middle East (black rhomb males white rhomb females)

diff erences in sexual dimorphism among species Th e measured data showed a sigmoid distribution pattern when plotted against age ( fi gs 2ndash5 ) so data were square root-transformed for the statistical analyses to meet the requirements for GLM (Tabachnick and Fidell 2001 Quinn and Keough 2002 )

Results

Factors included in the fi nal model were lsquoagersquo ( F 4 547 = 52176 p lt 00001) lsquosexrsquo ( F 4 547 = 4672 p lt 00001) lsquospeciesrsquo ( F 12 1448 = 2206 p = 00001) and the interaction term of lsquospecies by sexrsquo ( F 12 1448 = 316 p = 00001) When considering the diff erent dependent variables separately all traits considered increased with increasing age (fac-tor lsquoagersquo in table 1 fi gs 2 - 5 ) All measured variables were sexually dimorphic ie males had longer horns wider necks etc (factor lsquosexrsquo in table 1 fi gs 2 - 5 ) Th e interac-tion term of lsquospecies by sexrsquo was statistically signifi cant for all measured variables except for shoulder height ( table 1 ) suggesting that sexual dimorphism in all traits but shoul-der height diff ered across populations ( fi gs 2 - 5 )

Qualitatively sexual dimorphism often diff ered strikingly among taxa ( table 2 ) For example in G gazella lsquophenotype Brsquo horn length of females reached only 357 of that seen in males and neck circumference of females was 659 of that of males ( table 2 ) It is notable that female G gazella lsquophenotype Brsquo are slightly heavier than


0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

G Gazella lsquophenotype Arsquo


G dorcas

G s marica

Nec

k ci

rcum

fere

nce

(cm

)

Age (years)

Figure 4 Sexual dimorphism in neck circumference of four gazelle taxa ( Gazella gazella lsquophenotype Arsquo Gazella dorcas lsquo Gazella gazella lsquophenotype Brsquo Gazella subgutturosa marica ) inhabiting the Middle East (black rhomb males white rhomb females)

0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

G gazella lsquophenotype Arsquo


G dorcas

G s marica

Body

wei

ght (

kg)

Age (years)

Figure 3 Sexual dimorphism in body weight of four gazelle taxa ( Gazella gazella lsquophenotype Arsquo Gazella dorcas lsquo Gazella gazella lsquophenotype Brsquo Gazella subgutturosa marica ) inhabiting the Middle East (black rhomb males white rhomb females)


Shou

lder

hei

ght (

cm)

Age (years)

40

45

50

55

60

65

70

75

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75


G gazellalsquo phenotype Brsquo G s marica

G dorcas

Figure 5 Sexual dimorphism in shoulder height of four gazelle taxa ( Gazella gazella lsquophenotype Arsquo Gazella dorcas lsquo Gazella gazella lsquophenotype Brsquo Gazella subgutturosa marica ) inhabiting the Middle East (black rhomb males white rhomb females)

Table 1 Results from a multivariate GLM using horn length shoulder height body weight and neck circumference as dependent variables

df Mean square F p

Horn length age 1 5034 11843 lt 00001 species 3 496 1166 lt 00001 sex 1 1553 3653 lt 00001 species sex 3 241 566 0001Body weight age 1 1216 17499 lt 00001 species 3 110 1587 lt 00001 sex 1 124 1784 lt 00001 species sex 3 019 278 0040Shoulder height age 1 056 8314 lt 00001 species 3 008 1125 lt 00001 sex 1 013 1795 lt 00001 species sex 3 001 126 0288Neck circumference age 1 145 9785 lt 00001 species 3 013 849 lt 00001 sex 1 229 15450 lt 00001 species sex 3 004 269 0046

404 T Wronski et al Animal Biology 60 (2010) 395ndash412 Ta

ble

2

Adul

t m

ale

and

fem

ale

horn

len

gth

bod

y w

eigh

t an

d ne

ck c

ircum

fere

nce

for

the

four

gaz

elle

tax

a in

clud

ed i

n ou

r stu

dy

Giv

en a

re m

ean

plusmn S

E a

nd

(min

imum

ndash m

axim

um)

H

orn

leng

th [c

m]

Body

wei

ght [

kg]

Nec

k ci

rcum

fere

nce

[cm

]Sh

ould

er h

eigh

t [cm

]

m

ale

fem

ale

mal

efe

mal

em

ale

fem

ale

mal

efe

mal

e

G g

azell

a lsquop

heno

type

Arsquo

243

plusmn 0

512

5 plusmn

03

213

plusmn 0

717

2 plusmn

04

291

plusmn 0

520

9 plusmn

02

660

plusmn 0

562

8 plusmn

09

(20

2 ndash

280

)(8

0 ndash

17

5)(1

45

ndash 27

0)

(80

ndash 2

20)

(24

5 ndash

340

)(1

85

ndash 26

0)

(62

0 ndash

720

)(1

95

ndash 70

5)

G g

azell

a lsquop

heno

type

Brsquo

228

plusmn 0

68

1 plusmn

08

149

plusmn 0

615

3 plusmn

13

286

plusmn 0

818

8 plusmn

03

580

plusmn 0

653

4 plusmn

05

(19

3 ndash

260

)(5

4 ndash

10

8)(1

00

ndash 18

0)

(90

ndash 1

90)

(23

0 ndash

320

)(1

70

ndash 20

0)

(55

0 ndash

610

)(5

00

ndash 55

0)

G d

orca

s 21

2 plusmn

14

203

plusmn 1

818

5 plusmn

15

141

plusmn 0

729

0 plusmn

10

223

plusmn 0

367

5 plusmn

05

639

1 plusmn

04

(97

5 ndash

260

)(8

5 ndash

26

0)(1

70

ndash 20

0)

(11

0 ndash

170

)(2

80

ndash 30

0)

(21

0 ndash

240

)(6

70

ndash 68

0)

(61

0 ndash

04)

G s

ubgu

tturo

sa

mar

ica

334

plusmn 0

422

5 plusmn

03

196

plusmn 0

417

4 plusmn

02

291

plusmn 0

422

2 plusmn

01

649

plusmn 0

361

9 plusmn

02

(26

5 ndash

425

)(1

40

ndash 28

5)

(15

0 ndash

280

)(1

10

ndash 24

0)

(15

0 ndash

360

)(1

90

ndash 26

0)

(60

0 ndash

720

)(5

40

ndash 67

0)


males reaching 1029 of malesrsquo body weight By contrast sexual dimorphism was far less pronounced in the closely related G gazella lsquophenotype Arsquo with femalesrsquo horns reaching 515 of the male horn length and femalesrsquo neck circumference reaching 719 of the male neck circumference However G gazella lsquophenotype Arsquo females reached only 805 of malesrsquo body weight ( table 2 )

Discussion

Diff erences in male horn length

We found male horns to be approximately of the same lengths in three of the examined taxa but markedly longer in Sand gazelle ( G subgutturosa marica ) males (see mean values in table 2 fi g 2 ) Why do male Sand gazelles have longer horns During the dry season Sand gazelles are highly gregarious forming huge aggregations during migra-tion in search of green pasture (Legge and Rowley-Conwy 1987 Mendelssohn 1974 ) During the rutting season males occupy small temporary territories so males typically are surrounded by several neighbours and face constantly high mate competition (Habibi et al 1993 ) In Th omsonrsquos gazelle ( Eudorcas thomsoni ) which has a similar social organisation and migration pattern horns in adult males are also well developed (app 25-43 cm Brooks 1961 Gentry 1971 Halthenorth and Diller 1977 ) while those of the closely related Red-fronted gazelle ( E rufi frons ) are comparatively short (app 22-35 cm Groves 1969 Gentry 1964 Halthenorth and Diller 1977 ) Red-fronted gazelles live in small groups or pairs and migrate only over short distances fol-lowing the rains (Dorst and Dandelot 1970 Montfort et al 2001 Nchanji et al 2002) so of all species included in this study their biology resembles most that of G dorcas (see above Study species)

Th e average group size therefore seems to be the most reliable predictor for large weaponry in males even if the confounding eff ect of body size is controlled for (Roberts 1996 ) Inter-individual distances typically decrease as a function of group size (Risenhoover and Bailey 1985 Prins 1989 ) and can result in higher frequencies of agonistic interactions per individual (Marker 1956 Patterson 1965 Zucker 1974 Vestal and Vander-Stoep 1978 Rutberg 1983 ) so possession of weaponry can ulti-mately lead to substantial reproductive advantages

Diff erences in female horn length

Th e interaction term of lsquosex by speciesrsquo was signifi cant for horn length ( table 1 ) sug-gesting diff erences in sexual dimorphism among taxa Th is eff ect was driven primarily by females having considerably shorter horns than males in G gazella lsquophenotype Arsquo and G gazella lsquophenotype Brsquo whereas female horns are well developed and almost as long as those of the males in G subgutturosa marica and G dorcas ( table 2 fi g 2 )

Several hypotheses consider the question of why females in some bovid species have horns at all Given that many bovid females are hornless (eg half of the African gen-era Packer 1983 ) an adaptive explanation for female horns seems more likely rather


than purely a correlated genetic response to the development of horns in conspecifi c males (Lande 1980 Roberts 1996 )

(1) Th e predator defence hypothesis suggests that female horns function as a means of defence against predator attacks (Darling 1937 Kingdon 1982 Packer 1983 ) However observations of active defence in small- to medium-sized bovids are actually rare (Walther 1966 Estes 1991a ) and restricted to only few bovid species (eg waterbuck Spinage 1969 reedbuck Jungius 1970 wildebeest Watson 1969 ) For gazelles such behaviour is known only from Th omson gazelle where females may defend calves against jackal attacks (Walther 1968 1969 ) Also in many species horn shape is unsuited for eff ective defence and there is no evidence for prey selection by predators towards species with hornless females (Walther 1966 Roberts 1996 Estes 1991a )

(2) Th e intra-specifi c competition hypothesis suggests that female horns func-tion in the context of feeding competition with males and or avoidance of sexual harassment by males especially adolescent ones (Geist 1974a b 1977 Janis 1982 ) However even the highest degree of isomorphism (as seen in alcelaphine and hippotragine antelopes) appears not to lead to female dominance over immature malesmdashmales still become dominant once they reach the body size of females (Estes 1991a )

(3) Th e female competition hypothesis proposes that female horns have evolved in response to competition for limiting resources with other group mem-bers (mostly other females) Th e limiting resource is typically food or access to feeding sites but can also be the position within the herd (Hamilton 1971 ) or access to attractive mates (Balmford et al 1992 Bro-Joslashrgensen 2002 2007 Kokko and Jennions 2007 ) Solitary species or species living in small groups (like G gazella ) are less likely to defend resources against group members and consequently females do not develop horns or horns are at least strongly reduced in size (Jarman 1974 Leuthold 1977 Roberts 1996 ) By contrast increased competition between group members in more gregarious species (which is the case at least temporarily for G subgutturosa marica and G dorcas ) may have selected for enlarged horns in the female sex (Roberts 1996 )

(4) Finally the andromimicry hypothesis suggests that females may mimic the phenotype of their juvenile male off spring thereby raising the threshold for male aggression against adolescent male off spring and enabling their male off spring to leave the group at a later stage (Estes 1991a ) Th is hypothesis is intrinsically diffi cult to test manipulations of female phenotypes would need to be accompanied by long-term behavioural observations It needs to be stressed though that this hypothesis also predicts that females in gregari-ous species should have larger horns


It was argued in this context that a high polygeny potential has produced intense peer competition to develop large horns in Eudorcas thomsoni females (Brooks 1961 ) while at the same time the proximity of bachelor herds lowers the costs of early dispersal for male off spring Horn mimicry in females therefore seems unnecessary and ineff ective (Estes 1991a ) Th e Sudanese subspecies ( E thomsoni albonotata ) which lives in smaller groups at lower densities and in which male horns are smaller than in the nominate subspecies also have relatively well developed horns in the female sex (Groves 1969 Gentry 1971 )

Comparing G gazella lsquophenotypes A and Brsquo

Another focus of our current study was on the within-taxon variation of sexual dimor-phism between G gazella lsquophenotype Arsquo and lsquophentype Brsquo which appears as interesting as between-taxon diff erences In contradiction to a lack of marked genetic diff erence between the two phenotypes at neutral molecular markers sexual horn dimorphism was most pronounced in G gazella lsquophenotype Brsquo where the greatest sexual dimor-phism in horn length was detected and female horns are often barely visible Th e gen-eral biology of this taxon is completely unknown Since not even the exact origin of the examined animals is known no information is available with respect to the natural habitat and social organisation

Considering the small number of lsquophenotype Brsquo individuals surviving in captivity caution is required when interpreting the data at hand Very small horns in lsquophenotype Brsquo females may still be attributed to an inbreeding eff ect that may have already occurred in small remnant populations in the wild and or subsequently during the intensive breeding in captivity at KKWRC A signifi cant increase in hornlessness or malformed or reduced horns in females are also observed in the isolated island population of lsquo Gazella gazella farasani rsquo which inhabits a small archipelago (Farasan Islands) in the Red Sea (Th ouless and Al Basri 1991)

Apart from extreme sexual dimorphism in horn length lsquophenotype Brsquo shows a pro-nounced sexual dimorphism in neck circumference While neck circumference and horn length are smaller in females the diff erence in body weight is actually reduced to almost equal body weight in both sexes Compared to G gazella lsquophenotype Arsquo this diff erence is mainly due to a reduction in male body weight rather than an increase in female body weight It remains obscure why males have reduced body weight in this taxon since well-developed horns suggest that a general relaxation of sexual selection is unlikely to cause this pattern Isaac ( 2005 ) explained female-biased sexual body size dimorphism by reduced malendashmale competition resulting in a decrease in male size Femalendashfemale competition for dominance and resources including mates may also select for increased female size (Peacuterez-Barberia et al 2001 Isaac 2005 ) Ralls ( 1976 ) however has suggested that female-biased sexual size dimorphism is rarely the result of sexual selection acting on females but may result from selection favoring smaller males Blackenhorn et al (1995) suggested that female-biased sexual size dimorphism may be explained by the lsquosmall-male advantage hypothesisrsquo In mating systems where male reproductive success is primarily related to encounter rates with females small males may be favoured when food is limiting because they require lower absolute amounts of


food Th us given a trade-off between foraging and mate acquisition small males may be able to devote more time to the latter (Blackenhorn et al 1995 ) Future research on female mate choice and male mating tactics in our captive breeding stocks may provide important new insights in this direction

Acknowledgements

We would like to thank H H Prince Bandar bin Saud bin Mohammed al Saud (Secretary General NCWCD Saudi Arabia) for his permission and support to con-duct scientifi c research on wildlife in the Kingdom Special thanks are rendered to Ernest Robinson who supported this study to be carried out at KKWRC and who kindly commented and helped to improve previous manuscript drafts We would like to thank the following people for help with data collection Mohammed Hassan Jimmy Gatchalian Ismail Sir Al Khatim Mubarak Al Haj Sami Farooq Hamza Abdul Raheem Mohammed Al Zubair Swar Mohammad Ali Ambegoda Anil Rasika Sanjiiwa Amith Chandana and Lamberto Tamorada

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Allen GM ( 1940 ) Th e mammals of China and Mongolia Part 2 Th e American Museum of Natural History New York

Andersson M ( 1994 ) Sexual selection Princeton University Press Princeton Ansell WFH ( 1971 ) Artiodactyla In J Meester amp HW Setzer (Eds) Th e mammals of Africa An

Identifi cation Manual pp 1 - 84 Smithonian Institution Press Washington DC Baharav D ( 1980 ) Habitat utilization of dorcas gazelle in a desert saline area J Arid Environ 30 161 -

167 Baharav D ( 1981 ) Food habits of mountain gazelles in semi-arid habitats of eastern Lower Galilee Israel

J Arid Environ 4 63 - 69 Baharav D ( 1983 ) Reproductive strategies in female mountain and dorcas gazelles ( Gazella gazella gazella

and Gazella dorcas ) J Zool (Lond) 200 445 - 453 Baharav D ( 1985 ) Optimal foraging in Dorcas gazelles J Arid Environ 9 167 - 171 Balmford A Rosser AM amp Albon SD ( 1992 ) Correlates of female choice in resource-defending

antelope Behav Ecol Sociobiol 31 107 - 114 Blackenhorn WU Prezoisi RF amp Fairbairn DJ ( 1995 ) Time and energy constraints and the evolution

of sexual size dimorphism ndash to eat or to mate Evol Ecol 9 369 ndash 381 Bro-Joslashrgensen J ( 2002 ) Overt female mate competition and preference for central males in a lekking

antelope Proc Natl Acad Sci USA 99 9290 - 9293 Bro-Joslashrgensen J ( 2007 ) Th e intensity of sexual selection predicts weapon size in male bovids Evolution

61 ( 6 ) 1316 - 1326 Brooks AC ( 1961 ) A study of Th omsonrsquos gazelle in Tanganyika Colonial Research Publication No 25

HMSO London Campbell P ( 1997 ) A note on growing season food habits of mountain gazelles and Nubian ibex in Saudi

Arabia J Arid Environ 36 705 - 709 Carlisle DB amp Ghobrial LI ( 1968 ) Food and water requirements of Dorcas gazelle in the Sudan

Mammalia 32 571 - 576


Caro TM Graham CM Stoner CJ amp Flores MM ( 2003 ) Correlates of horn and antler shape in bovids and cervids Behav Ecol Sociobiol 55 32 - 41

Clutton-Brock TH Albon SD amp Harvey PH ( 1980 ) Antlers body size and breeding system in the Cervidae Nature 337 260 - 262

Cunningham PL amp Sandouka MA (submitted) Morphological characteristics and ageing criteria of reem gazelle ( Gazella subgutturosa marica Th omas 1897) and their use for management

Darling FF ( 1937 ) A herd of deer Oxford University Press Oxford Darwin C ( 1871 ) Th e descent of man and selection in relation to sex Murray London Dorst J amp Dandelot P ( 1970 ) Saumlugetiere Afrikas Paul Parey Berlin Hamburg Dunham KM ( 1998 ) Spatial organization of mountain gazelles Gazella gazella reintroduced to central

Arabia J Zool (Lond) 245 371 - 384 Dunham KM ( 1999 ) Th e social organization of mountain gazelles Gazella gazella in a population

reintroduced to central Arabia J Arid Environ 43 251 - 266 Essghaier JR amp Morrison-Scott TCS ( 1981 ) Distribution and use of dung heaps by dorcas gazelle

Gazella dorcas in western Libya Mammalia 45 153 - 156 Estes RD ( 1974 ) Social organisation of the Afrcan Bovidae In V Geist amp FR Walther (Eds) Th e

behaviour of ungulates in relation to management pp 166 - 205 IUCN Morges Switzerland Estes RD ( 1991a ) Th e signifi cance of horns and other male secondary sexual characters in female bovids

Appl Anim Behav Sci 29 403 - 451 Estes RD ( 1991b ) Th e behavior guide to African mammals University of California Press Berkley Ewer RF ( 1976 ) Ethologie der Saumlugetiere Paul Parey Berlin Geist V ( 1966 ) Th e evolution of horn-like organs Behaviour 27 175 - 214 Geist V ( 1974a ) On the relationship of social evolution and ecology in ungulates Ann Rev Ecol Syst 8

193 - 207 Geist V ( 1974b ) On the relationship of ecology and behavior in the evolution of ungulates Th eoretical

considerations In V Geist amp FR Walther (Eds) Th e behaviour of ungulates in relation to manage-ment pp 235 - 246 IUCN Morges Switzerland

Geist V ( 1977 ) A comparison of social adaptations in relation to ecology in gallinaceous bird and ungu-late societies Ann Rev Ecol Syst 8 193 - 208

Gentry AW ( 1971 ) Genus Gazella In J Meester amp HW Setzer (Eds) Th e mammals of Africa An Identifi cation Manual pp 85 - 93 Smithonian Institution Press Washington DC

Ghobrial LI ( 1974 ) Water relation and requirements of the dorcas gazelle in Sudan Mammalia 38 88 - 107

Greth A amp Williamson D ( 1996 ) Recent developments in gazelle conservation and taxonomy in Saudi Arabia In A Greth C Magin amp M Ancrenaz (Eds) Conservation of Arabian gazelles pp 8 - 39 National Commission for wildlife Conservation and Development Riyadh Saudi Arabia

Groves CP ( 1969 ) On the smaller gazelles of the genus Gazella de Blainville 1916 Z Saumlugetierk 34 38 - 60

Groves CP ( 1981 ) Notes on gazelles 3 Th e dorcas gazelles of North Africa Anali del Museo Civico di Storia Naturalle de Genova 83 455 - 471

Groves CP ( 1996 ) Taxonomic deversity in Arabian gazelles Th e state of the art In A Greth C Magin amp M Ancrenaz (Eds) Conservation of Arabian gazelles pp 8 - 39 National Commission for wildlife Conservation and Development Riyadh Saudi Arabia

Groves CP ( 1997 ) Th e taxonomy of Arabian gazelles In K Habibi HA Abuzinada amp IA Nader (Eds) Th e Gazelles of Arabia pp 24 - 51 National Commission for Wildlife Conservation and Development Riyadh Saudi Arabia

Habibi K ( 1991 ) Arabian Gazelles National Commission for Wildlife Conservation and Development Riyadh

Habibi K ( 1992 ) Reproductive strategy of the Farasan gazelle Gazella gazella farasani J Arid Environ 23 351 - 353

Habibi K Th ouless CR amp Lindsay N ( 1993 ) Comparative behaviour of sand and mountain gazelles J Zool (Lond) 229 41 - 53


Halthenorth T amp Diller H ( 1977 ) Saumlugetiere Afrikas BLV Muumlnchen Berlin Wien Hamilton WD ( 1971 ) Geometry for the selfi sh herd J Th eor Biol 31 295 - 311 Hammond R L Al Khaldy A Macasero W Flores B Mohammed O Al Saggaf M Wacher T

Bruford M amp Winney B ( 2000 ) Th e application of molecular genetics to the conservation of Arabian gazelles Report to King Abdulaziz City for Science and Technology General Directorate of Research Grants Programmes Riyadh

Harrison DL ( 1968 ) Mammals of Arabia Vol 2 Ernest Benn London Harrison DL amp Bates PJJ ( 1991 ) Th e Mammals of Arabia Harrison Zoological Museum Sevenoaks Heptner VG Nasimovich AA amp Bannikov AG ( 1988 ) Mammals of the Soviet Union Vol 1

Artiodactyla and Perissodactyla Smithsonian Institution Libraries and the National Science Foundation Washington

Hufnagel E ( 1972 ) Libyan Mammals Oleander Press Cambridge Isaac JL ( 2005 ) Potential causes and life-history consequences of sexual size dimorphism in mammals

Mammal Rev 35 ( 1 ) 101 ndash 115 Jamsheed R ( 1976 ) Big game animals of Iran (Persia) Rashid Jamsheed Th eheran Janis CM ( 1982 ) Evolution of horns in ungulates ecology and palaeoecology Biol Rev Cambr Phil

Soc 57 261 - 318 Jarman P ( 1974 ) Th e social organization of antelope in relation to their ecology Behaviour 48 215 -

267 Jarman P ( 1983 ) Mating systems and sexual dimorphism in large terrestrial mammalian herbivores

Biol Rev Cambr Phil Soc 58 485 - 520 Jungius H ( 1971 ) Studies on the breeding biology of reedbuck ( Redunca aurundium Boddaert 1785) in

the Kruger National Park Z Saumlugetierk 35 129 - 146 Karino K and Haijima Y ( 2001 ) Heritability of male secondary sexual traits in feral guppies in Japan

J Ethol 19 33 ndash 37 Kichenside TB ( 1998 ) Gazelle husbandry at King Khalid Wildlife Research centre Riyadh with special

reference to capture and handling Int Zoo Yearb 36 228 - 234 Kichenside TB amp Lindsay N ( 1997 ) Th e husbandry of gazelles at King Khalid Wildlife Research

Centre In K Habibi HA Abuzinada amp IA Nader (Eds) Th e Gazelles of Arabia pp 219 - 230 National Commission for Wildlife Conservation and Development Riyadh Saudi Arabia

Kingdon J ( 1982 ) East African mammals III Parts C amp D (Bovids) Academic Press London Kingswood SC amp Blank DA ( 1996 ) Gazella subgutturosa Mammalian Species 518 1 - 10 Kokko H amp Jennions MD ( 2007 ) Sexual confl ict the battle of the sexes reversed Curr Biol 18 ( 3 )

121 - 123 Kruuk H ( 1972 ) Th e spotted hyena University of Chicago Press Chicago Lande R ( 1980 ) Sexual dimorphism sexual selection and adaption in polygenic characters Evolution

34 292 - 307 Legge AJ amp Rowley-Conwy PA ( 1987 ) Gazelle killing in Stone Age Syria Sci Am 258 ( 2 ) 76 - 83 Loison AJ Gaillard JM Peacutelabon C amp Yoccoz NG ( 1999 ) What factors shape sexual size dimor-

phism in ungulates Evol Ecol Res 1 611 - 633 Mendelssohn H ( 1974 ) Th e development of the population of gazelles in Israel and their behavioural

adaptations IUCN New Series 24 722 - 743 Mendelssohn H amp Yom-Tov Y ( 1987 ) Th e mammals of Israel In A Alon (Ed) Plants and animals of

the land of Israel An Illustrated Encyclopedia Vol 7 pp 112 Ministry of Defense Publishing House and Society for the Protection of Nature Tel Aviv Israel

Mendelssohn H Yom-Tov Y and Groves CP ( 1995 ) Gazella gazella Mammalian Species 490 1 - 7 Mendelssohn H Groves CP amp Shalom B ( 1997 ) A new subspecies of Gazella gazella from the south-

ern Negev Israel J Zool 43 209 - 215 Mohamed SA Abbas J amp Saleh M ( 1991 ) Natural diet of the Arabian rheem gazelle Gazella subgut-

turosa marica J Arid Environ 20 371 - 374 Monfort SL Newby J Wacher T Tubiana J amp Moksia D ( 2001 ) Sahelo-Saharan Interest group

(SSIG) Wildlife Surveys Part 1 Central and Western Chad ZSL Conservation Report No 1 Zoological Society of London London


Morrison-Scott TCS ( 1939 ) Some Arabian mammals collected by Mr H St J B Philby CIE Novitates Zoologicae 41 181 - 211

Nchanji AC amp Amubode FO ( 2002 ) Th e physical and morphological characteristics of the red-fronted gazelle ( Gazella rufi frons kanuri Gray 1846) in Waza National park Cameroon J Zool (Lond) 256 505 - 509

Packer C ( 1983 ) Sexual dimorphism Th e horns of African antelopes Science 221 1191 - 1193 Patterson IJ ( 1965 ) Timing and spacing of boods in the black-headed gull Larus ridibundus Ibis 107

433 - 460 Peacuterez-Barberia FJ amp Gordon IJ ( 2000 ) Diff erences in body mass and oral morphology between the

sexes in the Artiodactyla evolutionary relationships with sexual segregation Evol Ecol Res 2 667 - 684

Peacuterez-Barberia FJ Gordon IJ amp Pagel M ( 2002 ) Th e origin of sexual dimorphism in body size in ungulates Evolution 56 1276 - 1285

Pienaar U de V ( 1969 ) Predator-prey relationships amongst the larger mammals of the Kruger National Park Koedoe 12 108 - 176

Prins HHT ( 1989 ) Buff alo herd structure and its repercussion for condition of individual African buf-falo cows Ethology 81 47 - 71

Popp JW ( 1985 ) Horn size and body size among antelopes Saumlugetierk Mitt 32 245 - 248 Quinn GP amp Keough MJ ( 2002 ) Experimental design and data analysis for biologists Cambridge

University Press Cambridge Ralls K ( 1976 ) Mammals in which females are larger than males Q Rev Biol 51 245 - 276 Risenhoover KL amp Bailey JA ( 1985 ) Relationship between group size feeding time and agonistic

behaviour of mountain goats Can J Zool 63 2501 - 2506 Roberts SC ( 1996 ) Th e evolution of hornedness in female ruminants Behaviour 133 399 - 442 Robertson F 1995 Food plants of gazelles and ibex in the Ibex Reserve Report King Khalid Wildlife

Research Centre Th umamah Rutberg AT ( 1983 ) Factors infl uencing dominance status in American bison cows ( Bison bison )

Z Tierpsychol 63 206 - 212 Ryan MJ ( 1985 ) Th e Tuacutengara frog a study in sexual selection and communication University of Chicago

Press Chicago Shuster SM amp Wade MJ ( 2003 ) Mating systems and strategies Princeton University Press

Princeton Spinage CA ( 1969 ) Territoriality and social organisation of the Uganda defassa waterbuck Kobus defassa

ugandae J Zool (Lond) 159 329 - 361 Tabachnick BG amp Fidell LS ( 2001 ) Using multivariate statistics 4th ed Allyn and Bacon Boston Th ouless CR Grainger JG Shobrak M amp Habibi K ( 1991 ) Conservation status of gazelles in Saudi

Arabia Biol Conserv 58 85 - 98 Tobler M Schlupp I amp Plath M ( 2008 ) Does divergence in female mate choice aff ect male size distri-

butions in two cave fi sh populations Biol Lett 4 452 - 454 Vesey-Fitzgerald D F ( 1952 ) Wildlife in Arabia Oryx 1 232 ndash 235 Vestal BM amp Vander-Stoep A ( 1978 ) Eff ect of distance between feeders on aggression in captive cham-

ois ( Rupicapra rupicapra ) Appl Anim Ethol 4 253 - 260 Walther F ( 1961 ) Entwicklungszuumlge im Kampf- und Paarungsverhalten der Horntiere Jb Georg v Opel-

Freigehege 3 90 - 115 Walther F ( 1966 ) Mit Horn und Huf Paul Parey Berlin Hamburg Walther F ( 1968 ) Verhalten der Gazelle Neue Brehm Buumlcherei No 373 Ziemsen Wittenberg

Lutherstadt Walther F ( 1969 ) Flight behaviour and avoidance of predators in Th omsonrsquos gazelle ( Gazella thomsoni

Guumlnther 1884) Behaviour 34 184 - 221 Watson RM ( 1969 ) Reproduction of wildebeest Connochaetes taurinus albojubatus Th omas in the

Serengeti region and its signifi cance to conservation J Reprod Fertil Suppl 6 287 - 310 Weckerly F W ( 1998 ) Sexual size dimorphism infl uence of mass and mating system in the most dimor-

phic mammals J Mammal 79 33 - 52


Williamson DT Tatwany H Rietkerk FE Delima E amp Lindsay N ( 1992 ) Temperature liability in the Arabian sand gazelle OnguleacutesUngulates 91 349 ndash 352

Wronski T amp Sandouka MA ( 2008 ) Growth stages and ageing criteria of Arabian Mountain gazelles ( Gazella gazella Pallas 1766 Antilopinae Bovidae ) Mammal Biol doi101016jmambio200809001

Wronski T (submitted) Population density and home range size of re-introduced mountain gazelles ( Gazella gazella ) in relation to resource availability in the Ibex Reserve central Saudi Arabia

Wronski T Wacher T Hammond RL Winney B Hundertmark K Blacket MJ Mohammed OB Flores B Omer SA Macasero W Plath M Tiedemann R amp Bleidorn C ( 2010 ) Two reciprocally monophyletic mtDNA lineages elucidate the taxonomic status of Mountain gazelles ( Gazella gazella ) Systematics and Biodiversity 8 ( 1 ) 1 - 10

Yom-Tov Y amp Ilani G ( 1987 ) Th e numerical status of Gazella dorcas and Gazella gazella in the southern Negev Desert Israel Biol Conserv 40 245 - 253

Yom-Tov Y Mendelssohn H amp Groves CP ( 1995 ) Gazella dorcas Mammalian Species 491 1 - 6 Zuk M amp Kolluru GR ( 1998 ) Exploitation of sexual signals by predators and parasitoids Q Rev Biol

73 415 - 438 Zuk M Rotenberry JT amp Tinghitella RM ( 2006 ) Silent night adaptive disappearance of a sexual

signal in a parasitized population of fi eld crickets Biol Lett 2 521 - 524


through male competition for mates or in the form of intra-sexual selection via female choicemdashoften leads to the elaboration of male secondary sexual traits (causing sexual dimorphism Packer 1983 Andersson 1994 Loison et al 1999 Abraham 1998 Karino and Haijima 2001 Peacuterez-Barberia et al 2002 Isaac 2005 ) while natural selection can counteract this process (eg Ryan 1985 Zuk and Kolluru 1998 Zuk et al 2006 ) In the present study we make a fi rst attempt to study sexual selection in four gazelle taxaphenotypes ( Gazella spp) from the Middle East by investigating sexual dimorphism in several morphological traits (most importantly horn length) Th is study is intended as a starting point for future investigations comparing other (behavioural) aspects of sexual selection in some of the little investigated taxa included in this study like male mating tactics and aggressive behaviour and female mate choice

Sexual dimorphism in bovids horned males and hornless females

In most bovid species sexual dimorphism in size and shape of horns and body propor-tions is striking for example in many species females are hornless while males often have sophisticated weaponry (Ansell 1971 Jarman 1974 Estes 1974 ) Th is can be attributed to the fact that males compete for mating opportunities (Walther 1961 Geist 1966 Janis 1982 Jarman 1983 ) and thus horn size and structure can be pre-dictive of mating success (Clutton-Brock et al 1980 Popp 1985 Bro-Joslashrgensen 2007 ) Darwin ( 1871 ) was one of the fi rst to develop the hypothesis that sexual selec-tion is a major force driving the evolution of weaponry in bovid males He believed that male horns were selected primarily through their role in intra-sexual combat Following this line of interpretation female hornlessness in some bovid species would be due to natural selection countering the expression of weaponry eg because horns are energetically costly and or hamper an individualrsquos ability to escape from predators (Roberts 1996 ) Indeed smaller species (lt 25 kg) that rely on crypsis to avoid preda-tors typically have hornless females (Packer 1983 )

Other authors have highlighted the potential role of natural selection for the evolu-tion of bovid horns Indeed some species can use their horns in defence against carni-vore predators (Kruuk 1972 Pienaar 1969 ) and this function has been proposed as one potential explanation for the development of horned females in some species (Packer 1983 )

Estes ( 1991a ) suggested that the primary function of female hornsmdashwhere existentmdashis to mimic those of their adolescent male off spring (andromimicry) which is thought to prevent adult males in the group from chasing their male off spring away from the group herd On the other hand Geist ( 1977 ) and Janis ( 1982 ) argued that female horns function as weapons to reduce feeding competition with males Another formulation of that hypothesis states that female horns may discourage unwanted sex-ual harassment by sub-adult males (Geist 1974a b) Finally Roberts ( 1996 ) suggested that females may develop horns as weapons during competition for limiting resources (female competition hypothesis)






Study species

















Hor

n le

ngth

(cm

)

Age (years)

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17



G dorcas

G s marica



Results




0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40



G dorcas

G s marica

Nec

k ci

rcum

fere

nce

(cm

)

Age (years)


0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17



G dorcas

G s marica

Body

wei

ght (

kg)

Age (years)



Shou

lder

hei

ght (

cm)

Age (years)

40

45

50

55

60

65

70

75

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75



G dorcas



df Mean square F p



ble

2

Adul

t m

ale

and

fem

ale

horn

len

gth

bod

y w

eigh

t an

d ne

ck c

ircum

fere

nce

for

the

four

gaz

elle

tax

a in

clud

ed i

n ou

r stu

dy

Giv

en a

re m

ean

plusmn S

E a

nd

(min

imum

ndash m

axim

um)

H

orn

leng

th [c

m]

Body

wei

ght [

kg]

Nec

k ci

rcum

fere

nce

[cm

]Sh

ould

er h

eigh

t [cm

]

m

ale

fem

ale

mal

efe

mal

em

ale

fem

ale

mal

efe

mal

e

G g

azell

a lsquop

heno

type

Arsquo

243

plusmn 0

512

5 plusmn

03

213

plusmn 0

717

2 plusmn

04

291

plusmn 0

520

9 plusmn

02

660

plusmn 0

562

8 plusmn

09

(20

2 ndash

280

)(8

0 ndash

17

5)(1

45

ndash 27

0)

(80

ndash 2

20)

(24

5 ndash

340

)(1

85

ndash 26

0)

(62

0 ndash

720

)(1

95

ndash 70

5)

G g

azell

a lsquop

heno

type

Brsquo

228

plusmn 0

68

1 plusmn

08

149

plusmn 0

615

3 plusmn

13

286

plusmn 0

818

8 plusmn

03

580

plusmn 0

653

4 plusmn

05

(19

3 ndash

260

)(5

4 ndash

10

8)(1

00

ndash 18

0)

(90

ndash 1

90)

(23

0 ndash

320

)(1

70

ndash 20

0)

(55

0 ndash

610

)(5

00

ndash 55

0)

G d

orca

s 21

2 plusmn

14

203

plusmn 1

818

5 plusmn

15

141

plusmn 0

729

0 plusmn

10

223

plusmn 0

367

5 plusmn

05

639

1 plusmn

04

(97

5 ndash

260

)(8

5 ndash

26

0)(1

70

ndash 20

0)

(11

0 ndash

170

)(2

80

ndash 30

0)

(21

0 ndash

240

)(6

70

ndash 68

0)

(61

0 ndash

04)

G s

ubgu

tturo

sa

mar

ica

334

plusmn 0

422

5 plusmn

03

196

plusmn 0

417

4 plusmn

02

291

plusmn 0

422

2 plusmn

01

649

plusmn 0

361

9 plusmn

02

(26

5 ndash

425

)(1

40

ndash 28

5)

(15

0 ndash

280

)(1

10

ndash 24

0)

(15

0 ndash

360

)(1

90

ndash 26

0)

(60

0 ndash

720

)(5

40

ndash 67

0)



Discussion





















Acknowledgements


References














Mammalia 32 571 - 576























































































Study species

















Hor

n le

ngth

(cm

)

Age (years)

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17



G dorcas

G s marica



Results




0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40



G dorcas

G s marica

Nec

k ci

rcum

fere

nce

(cm

)

Age (years)


0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17



G dorcas

G s marica

Body

wei

ght (

kg)

Age (years)



Shou

lder

hei

ght (

cm)

Age (years)

40

45

50

55

60

65

70

75

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75



G dorcas



df Mean square F p



ble

2

Adul

t m

ale

and

fem

ale

horn

len

gth

bod

y w

eigh

t an

d ne

ck c

ircum

fere

nce

for

the

four

gaz

elle

tax

a in

clud

ed i

n ou

r stu

dy

Giv

en a

re m

ean

plusmn S

E a

nd

(min

imum

ndash m

axim

um)

H

orn

leng

th [c

m]

Body

wei

ght [

kg]

Nec

k ci

rcum

fere

nce

[cm

]Sh

ould

er h

eigh

t [cm

]

m

ale

fem

ale

mal

efe

mal

em

ale

fem

ale

mal

efe

mal

e

G g

azell

a lsquop

heno

type

Arsquo

243

plusmn 0

512

5 plusmn

03

213

plusmn 0

717

2 plusmn

04

291

plusmn 0

520

9 plusmn

02

660

plusmn 0

562

8 plusmn

09

(20

2 ndash

280

)(8

0 ndash

17

5)(1

45

ndash 27

0)

(80

ndash 2

20)

(24

5 ndash

340

)(1

85

ndash 26

0)

(62

0 ndash

720

)(1

95

ndash 70

5)

G g

azell

a lsquop

heno

type

Brsquo

228

plusmn 0

68

1 plusmn

08

149

plusmn 0

615

3 plusmn

13

286

plusmn 0

818

8 plusmn

03

580

plusmn 0

653

4 plusmn

05

(19

3 ndash

260

)(5

4 ndash

10

8)(1

00

ndash 18

0)

(90

ndash 1

90)

(23

0 ndash

320

)(1

70

ndash 20

0)

(55

0 ndash

610

)(5

00

ndash 55

0)

G d

orca

s 21

2 plusmn

14

203

plusmn 1

818

5 plusmn

15

141

plusmn 0

729

0 plusmn

10

223

plusmn 0

367

5 plusmn

05

639

1 plusmn

04

(97

5 ndash

260

)(8

5 ndash

26

0)(1

70

ndash 20

0)

(11

0 ndash

170

)(2

80

ndash 30

0)

(21

0 ndash

240

)(6

70

ndash 68

0)

(61

0 ndash

04)

G s

ubgu

tturo

sa

mar

ica

334

plusmn 0

422

5 plusmn

03

196

plusmn 0

417

4 plusmn

02

291

plusmn 0

422

2 plusmn

01

649

plusmn 0

361

9 plusmn

02

(26

5 ndash

425

)(1

40

ndash 28

5)

(15

0 ndash

280

)(1

10

ndash 24

0)

(15

0 ndash

360

)(1

90

ndash 26

0)

(60

0 ndash

720

)(5

40

ndash 67

0)



Discussion





















Acknowledgements


References














Mammalia 32 571 - 576

































































































Hor

n le

ngth

(cm

)

Age (years)

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17



G dorcas

G s marica



Results




0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40



G dorcas

G s marica

Nec

k ci

rcum

fere

nce

(cm

)

Age (years)


0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17



G dorcas

G s marica

Body

wei

ght (

kg)

Age (years)



Shou

lder

hei

ght (

cm)

Age (years)

40

45

50

55

60

65

70

75

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75



G dorcas



df Mean square F p



ble

2

Adul

t m

ale

and

fem

ale

horn

len

gth

bod

y w

eigh

t an

d ne

ck c

ircum

fere

nce

for

the

four

gaz

elle

tax

a in

clud

ed i

n ou

r stu

dy

Giv

en a

re m

ean

plusmn S

E a

nd

(min

imum

ndash m

axim

um)

H

orn

leng

th [c

m]

Body

wei

ght [

kg]

Nec

k ci

rcum

fere

nce

[cm

]Sh

ould

er h

eigh

t [cm

]

m

ale

fem

ale

mal

efe

mal

em

ale

fem

ale

mal

efe

mal

e

G g

azell

a lsquop

heno

type

Arsquo

243

plusmn 0

512

5 plusmn

03

213

plusmn 0

717

2 plusmn

04

291

plusmn 0

520

9 plusmn

02

660

plusmn 0

562

8 plusmn

09

(20

2 ndash

280

)(8

0 ndash

17

5)(1

45

ndash 27

0)

(80

ndash 2

20)

(24

5 ndash

340

)(1

85

ndash 26

0)

(62

0 ndash

720

)(1

95

ndash 70

5)

G g

azell

a lsquop

heno

type

Brsquo

228

plusmn 0

68

1 plusmn

08

149

plusmn 0

615

3 plusmn

13

286

plusmn 0

818

8 plusmn

03

580

plusmn 0

653

4 plusmn

05

(19

3 ndash

260

)(5

4 ndash

10

8)(1

00

ndash 18

0)

(90

ndash 1

90)

(23

0 ndash

320

)(1

70

ndash 20

0)

(55

0 ndash

610

)(5

00

ndash 55

0)

G d

orca

s 21

2 plusmn

14

203

plusmn 1

818

5 plusmn

15

141

plusmn 0

729

0 plusmn

10

223

plusmn 0

367

5 plusmn

05

639

1 plusmn

04

(97

5 ndash

260

)(8

5 ndash

26

0)(1

70

ndash 20

0)

(11

0 ndash

170

)(2

80

ndash 30

0)

(21

0 ndash

240

)(6

70

ndash 68

0)

(61

0 ndash

04)

G s

ubgu

tturo

sa

mar

ica

334

plusmn 0

422

5 plusmn

03

196

plusmn 0

417

4 plusmn

02

291

plusmn 0

422

2 plusmn

01

649

plusmn 0

361

9 plusmn

02

(26

5 ndash

425

)(1

40

ndash 28

5)

(15

0 ndash

280

)(1

10

ndash 24

0)

(15

0 ndash

360

)(1

90

ndash 26

0)

(60

0 ndash

720

)(5

40

ndash 67

0)



Discussion





















Acknowledgements


References














Mammalia 32 571 - 576



















































































0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 170

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40



G dorcas

G s marica

Nec

k ci

rcum

fere

nce

(cm

)

Age (years)


0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0

5

10

15

20

25

30

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17



G dorcas

G s marica

Body

wei

ght (

kg)

Age (years)



Shou

lder

hei

ght (

cm)

Age (years)

40

45

50

55

60

65

70

75

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75



G dorcas



df Mean square F p



ble

2

Adul

t m

ale

and

fem

ale

horn

len

gth

bod

y w

eigh

t an

d ne

ck c

ircum

fere

nce

for

the

four

gaz

elle

tax

a in

clud

ed i

n ou

r stu

dy

Giv

en a

re m

ean

plusmn S

E a

nd

(min

imum

ndash m

axim

um)

H

orn

leng

th [c

m]

Body

wei

ght [

kg]

Nec

k ci

rcum

fere

nce

[cm

]Sh

ould

er h

eigh

t [cm

]

m

ale

fem

ale

mal

efe

mal

em

ale

fem

ale

mal

efe

mal

e

G g

azell

a lsquop

heno

type

Arsquo

243

plusmn 0

512

5 plusmn

03

213

plusmn 0

717

2 plusmn

04

291

plusmn 0

520

9 plusmn

02

660

plusmn 0

562

8 plusmn

09

(20

2 ndash

280

)(8

0 ndash

17

5)(1

45

ndash 27

0)

(80

ndash 2

20)

(24

5 ndash

340

)(1

85

ndash 26

0)

(62

0 ndash

720

)(1

95

ndash 70

5)

G g

azell

a lsquop

heno

type

Brsquo

228

plusmn 0

68

1 plusmn

08

149

plusmn 0

615

3 plusmn

13

286

plusmn 0

818

8 plusmn

03

580

plusmn 0

653

4 plusmn

05

(19

3 ndash

260

)(5

4 ndash

10

8)(1

00

ndash 18

0)

(90

ndash 1

90)

(23

0 ndash

320

)(1

70

ndash 20

0)

(55

0 ndash

610

)(5

00

ndash 55

0)

G d

orca

s 21

2 plusmn

14

203

plusmn 1

818

5 plusmn

15

141

plusmn 0

729

0 plusmn

10

223

plusmn 0

367

5 plusmn

05

639

1 plusmn

04

(97

5 ndash

260

)(8

5 ndash

26

0)(1

70

ndash 20

0)

(11

0 ndash

170

)(2

80

ndash 30

0)

(21

0 ndash

240

)(6

70

ndash 68

0)

(61

0 ndash

04)

G s

ubgu

tturo

sa

mar

ica

334

plusmn 0

422

5 plusmn

03

196

plusmn 0

417

4 plusmn

02

291

plusmn 0

422

2 plusmn

01

649

plusmn 0

361

9 plusmn

02

(26

5 ndash

425

)(1

40

ndash 28

5)

(15

0 ndash

280

)(1

10

ndash 24

0)

(15

0 ndash

360

)(1

90

ndash 26

0)

(60

0 ndash

720

)(5

40

ndash 67

0)



Discussion





















Acknowledgements


References














Mammalia 32 571 - 576



















































































Shou

lder

hei

ght (

cm)

Age (years)

40

45

50

55

60

65

70

75

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75

40

45

50

55

60

65

70

75



G dorcas



df Mean square F p



ble

2

Adul

t m

ale

and

fem

ale

horn

len

gth

bod

y w

eigh

t an

d ne

ck c

ircum

fere

nce

for

the

four

gaz

elle

tax

a in

clud

ed i

n ou

r stu

dy

Giv

en a

re m

ean

plusmn S

E a

nd

(min

imum

ndash m

axim

um)

H

orn

leng

th [c

m]

Body

wei

ght [

kg]

Nec

k ci

rcum

fere

nce

[cm

]Sh

ould

er h

eigh

t [cm

]

m

ale

fem

ale

mal

efe

mal

em

ale

fem

ale

mal

efe

mal

e

G g

azell

a lsquop

heno

type

Arsquo

243

plusmn 0

512

5 plusmn

03

213

plusmn 0

717

2 plusmn

04

291

plusmn 0

520

9 plusmn

02

660

plusmn 0

562

8 plusmn

09

(20

2 ndash

280

)(8

0 ndash

17

5)(1

45

ndash 27

0)

(80

ndash 2

20)

(24

5 ndash

340

)(1

85

ndash 26

0)

(62

0 ndash

720

)(1

95

ndash 70

5)

G g

azell

a lsquop

heno

type

Brsquo

228

plusmn 0

68

1 plusmn

08

149

plusmn 0

615

3 plusmn

13

286

plusmn 0

818

8 plusmn

03

580

plusmn 0

653

4 plusmn

05

(19

3 ndash

260

)(5

4 ndash

10

8)(1

00

ndash 18

0)

(90

ndash 1

90)

(23

0 ndash

320

)(1

70

ndash 20

0)

(55

0 ndash

610

)(5

00

ndash 55

0)

G d

orca

s 21

2 plusmn

14

203

plusmn 1

818

5 plusmn

15

141

plusmn 0

729

0 plusmn

10

223

plusmn 0

367

5 plusmn

05

639

1 plusmn

04

(97

5 ndash

260

)(8

5 ndash

26

0)(1

70

ndash 20

0)

(11

0 ndash

170

)(2

80

ndash 30

0)

(21

0 ndash

240

)(6

70

ndash 68

0)

(61

0 ndash

04)

G s

ubgu

tturo

sa

mar

ica

334

plusmn 0

422

5 plusmn

03

196

plusmn 0

417

4 plusmn

02

291

plusmn 0

422

2 plusmn

01

649

plusmn 0

361

9 plusmn

02

(26

5 ndash

425

)(1

40

ndash 28

5)

(15

0 ndash

280

)(1

10

ndash 24

0)

(15

0 ndash

360

)(1

90

ndash 26

0)

(60

0 ndash

720

)(5

40

ndash 67

0)



Discussion





















Acknowledgements


References














Mammalia 32 571 - 576



















































































ble

2

Adul

t m

ale

and

fem

ale

horn

len

gth

bod

y w

eigh

t an

d ne

ck c

ircum

fere

nce

for

the

four

gaz

elle

tax

a in

clud

ed i

n ou

r stu

dy

Giv

en a

re m

ean

plusmn S

E a

nd

(min

imum

ndash m

axim

um)

H

orn

leng

th [c

m]

Body

wei

ght [

kg]

Nec

k ci

rcum

fere

nce

[cm

]Sh

ould

er h

eigh

t [cm

]

m

ale

fem

ale

mal

efe

mal

em

ale

fem

ale

mal

efe

mal

e

G g

azell

a lsquop

heno

type

Arsquo

243

plusmn 0

512

5 plusmn

03

213

plusmn 0

717

2 plusmn

04

291

plusmn 0

520

9 plusmn

02

660

plusmn 0

562

8 plusmn

09

(20

2 ndash

280

)(8

0 ndash

17

5)(1

45

ndash 27

0)

(80

ndash 2

20)

(24

5 ndash

340

)(1

85

ndash 26

0)

(62

0 ndash

720

)(1

95

ndash 70

5)

G g

azell

a lsquop

heno

type

Brsquo

228

plusmn 0

68

1 plusmn

08

149

plusmn 0

615

3 plusmn

13

286

plusmn 0

818

8 plusmn

03

580

plusmn 0

653

4 plusmn

05

(19

3 ndash

260

)(5

4 ndash

10

8)(1

00

ndash 18

0)

(90

ndash 1

90)

(23

0 ndash

320

)(1

70

ndash 20

0)

(55

0 ndash

610

)(5

00

ndash 55

0)

G d

orca

s 21

2 plusmn

14

203

plusmn 1

818

5 plusmn

15

141

plusmn 0

729

0 plusmn

10

223

plusmn 0

367

5 plusmn

05

639

1 plusmn

04

(97

5 ndash

260

)(8

5 ndash

26

0)(1

70

ndash 20

0)

(11

0 ndash

170

)(2

80

ndash 30

0)

(21

0 ndash

240

)(6

70

ndash 68

0)

(61

0 ndash

04)

G s

ubgu

tturo

sa

mar

ica

334

plusmn 0

422

5 plusmn

03

196

plusmn 0

417

4 plusmn

02

291

plusmn 0

422

2 plusmn

01

649

plusmn 0

361

9 plusmn

02

(26

5 ndash

425

)(1

40

ndash 28

5)

(15

0 ndash

280

)(1

10

ndash 24

0)

(15

0 ndash

360

)(1

90

ndash 26

0)

(60

0 ndash

720

)(5

40

ndash 67

0)



Discussion





















Acknowledgements


References














Mammalia 32 571 - 576




















































































Discussion





















Acknowledgements


References














Mammalia 32 571 - 576
































































































Acknowledgements


References














Mammalia 32 571 - 576


















































































Differences in sexual dimorphism among four gazelle taxa (Gazella spp.) in the Middle East

Documents

Transcript of Differences in sexual dimorphism among four gazelle taxa (Gazella spp.) in the Middle East