Multivariate Sexual Dimorphism, Sexual Selection, and Adaptation in Greater Antillean Anolis Lizards

Abstract

Sexual variation in body form is a common phenomenon in the natural world. Although most research has focused on dimorphism in size, examination of differences in shape can provide insight into ecological factors that may differ in importance to the sexes. In this study, we investigated the patterns of body shape dimorphism in 15 species of Greater Antillean Anolis lizards and investigated whether these patterns can be explained by allometry, phylogenetic effect, or sexual differences in habitat use.We found extensive shape and ecological variation between males and females. Previous studies have been conducted on males only; we found that females have also evolved morphologies to match their habitats. However, we concluded that adaptive patterns differ for the sexes and that interspecific ecological variation is related more strongly to shape than to size for each sex.Previous studies on males have revealed repeated convergent evolution of morphology to habitat types (termed ''ecomorphs''). Here, we found that ecomorphs also differ in the magnitude and direction of shape dimorphism. These results cannot be accounted for by allometric scaling or by phylogenetic similarity (regardless of assumptions regarding evolutionary process); they support previous studies that have found important life-history differences for species of different habitat types. We found some evidence for independent adaptation of the sexes, but with more complex ecological patterning occurring between sexes than can be explained by sexual selection alone. Consequently, some combination of functional differences and sexual selection is required.

Intersexual niche segregation in Cepero’s Ground-hopper, Tetrix ceperoi

“…Nevertheless, in the case of predation it is even more difficult to disentangle cause and effect. A differential predation risk might either be an effect of higher predation pressure on males due to their higher activity levels (Rowe 1994) or their displays in open habitats (Butler and Losos 2002), or it might be an effect of lower predation on females, which might select safer habitats in order to reduce the risk of predation (Bon et al 2001). Based upon our data, it is not possible to distinguish whether microhabitat choice is influenced by the predation risk or vice versa.…”

“…A number of studies have supported the dimorphic niches hypothesis (e.g., Shine 1991;Merilaita and Jormalainen 1997;Butler and Losos 2002;Ruckstuhl and Neuhaus 2002), but there is also evidence for intersexual competition in some taxa (Ardia and Bildstein 1997;Temeles et al 2000). However, in systems with high food availability intersexual competition for food is unlikely (Merilaita and Jormalainen 1997).…”

Sexual dimorphism in the skull geometry of newt species of Ichthyosaura, Triturus and Lissotriton (Salamandridae, Caudata, Amphibia)

“…If so, the patterns of sexual shape dimorphism are expected to be concordant with those of size (e.g. Butler and Losos 2002). Relatively small sample sizes per population and sex have limited our analyses of sex-and population-specific allometries.…”

Disentangling the Size and Shape Components of Sexual Dimorphism

“…Common hypotheses explaining sex-specific evolution in body size and shapes relate to female fecundity, intraspecific niche divergence and to sexual selection Electronic supplementary material The online version of this article (doi:10.1007/s11692-015-9313-z) contains supplementary material, which is available to authorized users. (Badyaev and Martin 2000;Butler and Losos 2002;Greenberg and Olsen 2010;Head 1995;Olsson et al 2002;Shine 1989). These varying selection pressures are expected to be reflected in sex-specific phenotypes.…”