When populations or species or sexes facing different competitive regimes, we should expect natural selection to act on aggressive and other competitive traits in different ways. We also should expect this process to shape the specific mechanisms underlying those competitive traits in males (Rosvall 2016a,b) and in females (Rosvall 2013). Postdoc Sara Lipshutz is investigating how competition for nesting territories may influence the evolution of female aggression and neuroendocrine mechanisms, by studying the repeated evolution of cavity nesting in songbirds. Sara is also comparing mechanisms of female aggression in the sex role-reversed Jacana system in Panama. Check out Sara’s page for details as they unfold!