Meeting Abstract
Understanding the maintenance of fitness-related traits remains at the very heart of evolutionary biology, with a wide variety of approaches focused on survival and reproductive processes. We have studied how hormones in the bank vole (Myodes glareolus) mediate phenotypic adaptation and trade-offs in the context of their social environment (density and frequency). Reproductive trade-offs within and between the sexes are mediated by hormones in this species: plasma testosterone (T) level and immunocompetence are both phenotypically and genetically negatively correlated. The benefits of greater T production on male reproductive success are balanced by both intrasexual (lower immunocompetence) and intersexual (lower reproductive success of daughters) fitness costs. T exerts sexually antagonistic effects on reproductive success through the opposing effects on female and male mating rates, thereby creating an evolutionary conflict of interest over this hormone. Given the various phenotypic effects and sexually dimorphic nature of T (and other hormone systems), we predict that most sexually antagonistic traits will be mediated by hormones and maintained by social factors of the environment.
