Meeting Abstract
In Sceloporus lizards, male blue abdominal patches are ancestral while absence of blue patches is derived and has evolved independently several times. In the several species that have been studied, early exposure to androgens hormonally organizes the skin and blue patches are permanently expressed in adult males. The blue is exposed with specific postural displays used during male-male aggression. Hence expression of male blue in a given species is likely to often be associated with higher levels of territorial display behavior and activity, both of which are androgen-mediated behaviors. We test the hypothesis that males in blue species will have higher breeding-season levels of testosterone than males in non-blue species. We selected blue-loss species and a closer blue relative of each, in several clades within Sceloporus. Analyses controlling for phylogeny (using phylogenetically independent contrasts and phylogenetic generalized least squares) revealed that, in species in which males are blue (grammicus, parvus, graciosus, occidentalis), both males and females have significantly higher plasma testosterone than the comparable sex in species in which males have lost the blue patches (megalepidurus, cozumelae, siniferus, virgatus). Hence breeding-season levels of testosterone appear to co-evolve with the presence of blue abdominal patches in males, and females may show correlated responses.
