Meeting Abstract
Androgens play important roles in the development, expression, and maintenance of the male reproductive system across a wide variety of species. Generally, androgens bind to androgen receptors (AR) to induce physiological changes to male sex organs and/or secondary sex characteristics. Anolis lizards provide a robust system for the study of androgen-regulated characteristics. In anoles, androgens are important regulators of social display behaviors (specifically throat fan, or dewlap, extensions and pushup displays) during the breeding season. However, interspecific variation in circulating testosterone levels in this genus is not associated with the frequency of dewlap display, suggesting another mechanism for the regulation of this behavior. In this study, we aimed to determine whether anole species with increased display behaviors exhibited an increased concentration of AR in the muscles controlling those behaviors. In six species of anoles that demonstrate significant variation in the frequency of dewlap and pushup displays, we measured the percentage of AR+ nuclei present in the ceratohyoid muscle (controlling dewlap extension) and the bicep muscle (controlling pushup display). Using phylogenetically-informed analyses, we found that species with a greater proportion of AR+ nuclei in the bicep exhibited higher rates of pushup displays; however, we did not find the same pattern in the dewlap-controlling muscle. These results suggest that AR expression may play a critical role in the evolution of social behaviors in this group, but because this pattern was not consistent across the muscles we examined, other mechanisms are likely to influence these behaviors as well.
