May 22 2019

4:00 pm Hershey Hall 158

Kimberly Rosvall
Indiana University

Female Competition and the Challenge Hypothesis


The bi-directional links between hormones and behavior have been a rich area of research for decades, perhaps especially so for the vertebrate sex steroid testosterone (T). Nearly 30 years ago, theory on the evolution of T levels was advanced by the challenge hypothesis, which presented a framework for understanding patterns of T secretion in males. By and large, interspecific, seasonal, and social variation in T levels in males appear to be shaped by the competing demands of parental care vs. male-male aggression. Female competition and aggression are also widespread\; however, it is unclear whether and how the challenge hypothesis applies to females. Research in my lab seeks to identify mechanisms of female aggression and how they evolve. We study the tree swallow (Tachycineta bicolor), a cavity-nesting bird for which social challenges from prospecting rivals pose a very real threat to territorial females. Our results demonstrate that female aggression is adaptive and mediated by T. However, seasonal changes in aggression do not mirror changes in T in circulation, suggesting that additional mechanisms must exist to allow for marked aggression in the face of low T. Here, I present data that integrate hormonal and genomic mechanisms across the brain and body, with the ultimate goal of developing a framework for understanding mechanisms of social competition in females and how they are shaped by natural selection.











































































































































































































































































































































































































































































































































































































this is idtest: