Sexual size dimorphism and allometry in Liolaemus of the L. laurenti group (Sauria: Liolaemidae): Morphologic lability in a clade of lizards with different reproductive modes

Abstract

Sexual size dimorphism is a common aspect in animals and different hypotheses to this regard were generated. Additionally, Rensch's rule is an empirical pattern that states that the degree of sexual size dimorphism is more pronounced in species with larger males, and less pronounced in those with larger females. We studied the body size differences, Rensch's rule and sexual dimorphism in morphological features in 22 lizard species of the Liolaemus laurenti clade. We assessed sexual dimorphism using independent contrasts and gauged phylogenetic signal in all measured traits. We intend to answer the following questions: (a) what is the phylogenetic signal of body size and other morphological features?; (b) do the Liolaemus lizards of the laurenti clade follow the Rensch's rule pattern?, and (c) do fecundity advantage or sexual selection hypotheses explain the differences between sexes?. Liolaemus species show low phylogenetic signal in most of the measured traits. In this group, male-larger dimorphism is more common, and several species showed no sexual size dimorphism. Additionally, our results do not support Rensch's rule. Head shape and radius length showed sexual dimorphism suggesting sexual selection. Finally, no relationship was recovered between inter-limb length and reproductive output, thus fecundity advantage hypothesis was not supported.