Meeting Abstract

85.3  Friday, Jan. 7  Persistent population differences in boldness behavior and stress physiology suggest rapid evolution following colonization of a novel environment ATWELL, Jonathan W.*; CARDOSO, Goncalo C.; WHITTAKER, Danielle J.; KETTERSON, Ellen D.; Indiana University; Centro de Investigação em Biodiversidade e Recursos Genéticos, Vairao, Portugal; Indiana University; Indiana University jwatwell@indiana.edu

Novel or changing environments expose animals to diverse and potentially deleterious stressors, and coordinated hormonal and behavioral adaptations are likely required for population persistence. Adaptation to urban living, for example, is predicted to include both attenuated endocrine responses to stress, as well as selection for ‘bolder’ (i.e. less neophobic) behavior, although few studies have evaluated divergence for associated hormonal and behavioral traits. Here we present unique evidence suggesting rapid and correlated adaptive shifts in both stress physiology and boldness behavior in a songbird, the dark-eyed junco, following its colonization of a novel environment. We compared corticosterone titres in birds from both a recently established urban population in San Diego, California to responses from a nearby wildland population in the ancestral montane breeding range. We also measured corticosterone and boldness behavior in a captive common garden study. We found persistent population differences in both corticosterone responses and exploratory boldness, as well as significant negative covariation between these traits in the common garden. Although early developmental effects cannot be ruled out, these results suggest contemporary evolution of correlated hormonal and behavioral traits post-colonization.