Sexual size and shape dimorphism in two species of newts, Triturus cristatus and T. vulgaris (Caudata: Salamandridae)

Malmgren, Jan C.; Thollesson, Mikael

doi:10.1017/s0952836999010018

Cited by 24 publications

(42 citation statements)

References 24 publications

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“…European newts have been the subject of many SSD studies, in which a number of conspecific and congeneric populations were examined (Kalezić et al. 1992; Malmgren 1999; Malmgren and Thollesson 1999). A female‐biased pattern of SSD was found to prevail, but with marked interspecies differences in the degree of dimorphism.…”

Section: Introductionmentioning

confidence: 99%

Sexual size and shape evolution in European newts (Amphibia: Caudata: Salamandridae) on the Balkan Peninsula

Ivanović

Sotiropoulos

Furtula³

et al. 2008

Journal of Zoological Systematics and Evolutionary Research

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We used a phylogenetic perspective in an examination of the direction and extent of sexual dimorphism in body size and body shape in European newts from the Balkan Peninsula (alpine newts, Mesotriton alpestris; crested newts, Triturus cristatus superspecies; smooth newts, Lissotriton vulgaris). We found a strong, female-biased sexual size dimorphism (SSD) in the analysed clades of alpine newt, whereas within crested newts we found a less stringent female-biased SSD in Triturus carnifex, Triturus macedonicus and Triturus karelinii, and no significant SSD in T. cristatus or Triturus dobrogicus. Among the smooth newts, we found male-biased SSD in Lissotriton vulgaris vularis and Lissotriton vulgaris greacus and no SSD in Lissotriton vulgaris meridionalis. Most of these newts also exhibit a significant sexual dimorphism in body shape, which varied more randomly than body size, regardless of SSD level. Female and male body size as well as the degree of SSD displayed statistically significant phylogenetic signal, while sexual dimorphism in body shape was phylogenetically independent. The relationship between independent contrast data for female size and male size indicated that SSD in European newts could be driven by a disproportionate increase in female size as increase in female size was not accompanied by a proportional increase in male size.

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Section: Introductionmentioning

confidence: 99%

Sexual size and shape evolution in European newts (Amphibia: Caudata: Salamandridae) on the Balkan Peninsula

Ivanović

Sotiropoulos

Furtula³

et al. 2008

Journal of Zoological Systematics and Evolutionary Research

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“…Most studies of sexual dimorphism in chelonians and other reptiles have concentrated on body size (Berry & Shine, 1980;Fitch, 1981;Wilbur & Morin, 1988;Gibbons & Lovich, 1990;Yasuka et al, 1996), but differences in shape are more likely to reflect sexual selection (Bonnet et al, 2001). Recent work on several animal groups has shown the value of shape in the study of sexual selection, particularly using analysis of covariance (ANCOVA) to compare characters in males and females adjusted for differences in body size (Bull & Pamula, 1996;Abell et al, 1999;Malmgren & Thollesson, 1999). Nevertheless, it may be difficult to distinguish between natural selection for fecundity and sexual selection for courtship success.…”

Section: Introductionmentioning

confidence: 99%

Sexual dimorphism of body size and shell shape in European tortoises

Willemsen¹,

Hailey

2003

Journal of Zoology

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Adult body size and shape were examined in almost 1400 individuals of the tortoises Testudo graeca, T. hermanni and T. marginata from Greece. The size at maturity was greater in females than in males in all three species. Maximum and mean adult sizes were also greater in females than in males in T. graeca and T. hermanni. Males grew to a larger size than females in T. marginata, and mean adult size was similar in the sexes in this species. Sexual dimorphism of shape (adjusted for size covariate) was shown in most of the characters examined, and the degree of this dimorphism differed significantly among the three species. Differences were related to their contrasting courtship behaviours: horizontal head movements and severe biting in T. marginata, vertical head bobs and carapace butting in T. graeca, and mounting and tail thrusting in T. hermanni. There was no difference in the frequency of observations of courtship or fighting among the three species, but courtship was about 10 times more common than combat in males. All species showed greatest courtship activity in autumn; copulation was rarely observed in T. hermanni (only 0.36% of courting males) and not seen in the other species in the field. Observations made throughout the activity season indicated that feeding was equally common in males and females in all three species. Differences in shape were more likely to be the result of sexual selection than of natural selection for fecundity. Detailed predictions are made for sexual dimorphism of other characters in these species.

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“…These studies provided important and detailed information on SSD and on many other sexually dimorphic traits. However, few studies have explored the links between the male and female reproductive roles and their influence on overall body shape (Bonnet et al, 1998;Allison et al, 1999;Malmgren & Thollesson, 1999), and none is available in chelonians.…”

Section: Introductionmentioning

confidence: 99%

Sexual dimorphism in steppe tortoises (Testudo horsfieldii): influence of the environment and sexual selection on body shape and mobility

Bonnet¹

2001

Biological Journal of the Linnean Society

123

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Selective forces shape sexes differently, with male body proportions facing strong selection to enhance mate searching and male-to-male combat traits, and female fitness being influenced by the ability to assimilate large amounts of nutrients necessary for vitellogenesis (and/or gestation), and their ability to carry the eggs or embryos. We evaluated the sexual dimorphism of body proportion of more than 800 wild steppe tortoises (Testudo horsfieldii) in Uzbekistan. The thick, well-developed shell offers protection from predators but pronounced digging habits probably also constrain body shape (e.g. a shell that is dorso-ventrally flattened, although round from a dorsal view helps to penetrate into, and move within the soil). Thus, in this species, natural selection might favour a heavy and flat shell that is 'closed' with small openings for appendages. In males, these environmental influences appear to be countered by sexual selection. Compared to females, they weigh less (absolutely and relative to shell dimensions), have longer legs, have shell structure allowing wider movements for their legs, and they walk faster. Males were also able to right themselves more quickly than females did in experimental tests. This quick righting ability is critical because intra-sexual combats frequently result in males being flipped onto their backs and becoming prone to hyperthermia or predation. Females are heavily built, with wide shells (relative to male shells), which may provide space for carrying eggs. From our results, a number of simple hypotheses can be tested on a wide range of chelonian species.

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Sexual size and shape dimorphism in two species of newts, Triturus cristatus and T. vulgaris (Caudata: Salamandridae)

Cited by 24 publications

References 24 publications

Sexual size and shape evolution in European newts (Amphibia: Caudata: Salamandridae) on the Balkan Peninsula

Sexual size and shape evolution in European newts (Amphibia: Caudata: Salamandridae) on the Balkan Peninsula

Sexual dimorphism of body size and shell shape in European tortoises

Sexual dimorphism in steppe tortoises (Testudo horsfieldii): influence of the environment and sexual selection on body shape and mobility

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