Hormones and Phenotypic Integration: Comparing Sexes, Individuals and Populations

Indiana University, Bloomington IN

Investigators

Abstract

Hormones integrate behavior and physiology by responding to environmental signals and altering gene expression in target tissues in the brain and the body. However, when the environment of a species changes, the most adaptive response might be to lose hormone sensitivity at some of the target tissues. An open question is whether hormone-mediated traits can be decoupled in such a way. This research will focus on the steroid hormone testosterone and its integrating effect on the behavior and physiology of males and females of a songbird species, the dark-eyed junco. The relative importance of phenotypic integration or independence of hormonally mediated traits has significant implications for the evolution of life histories, sex differences, and the formation of new species. The research will help to train future scientists of diverse backgrounds in the conduct of laboratory and field research that combines techniques and perspectives from multiple disciplines. Potential societal implications of the research include greater knowledge of the impact of hormonally active agents in the environment, and the ability of natural populations to respond effectively to environments altered by climate change.