38.4 Thursday, Jan. 5 Signal color drives seasonal oxidative stress and testosterone profiles in a songbird. VITOUSEK, Maren N.*; STEWART, Rosemary A.; SAFRAN, Rebecca J.; University of Colorado, Boulder; Indiana University; University of Colorado, Boulder email@example.com
Social interactions are commonly mediated by morphological signals. To present reliable information, signals should reflect an individual’s ability to physiologically cope with challenges, both social and ecological. However, it is unclear how static morphological signals convey accurate information about dynamic physiological parameters. Here we report that the seasonal physiological profile of female barn swallows, Hirundo rustica, is driven by static signal expression. Females manipulated to display darker ventral plumage decreased oxidative stress, reactive oxygen metabolites, and testosterone, thereby adopting the physiological profile of naturally darker individuals. Signal-hormone relationships in females were opposite those documented in males, suggesting that the same trait conveys different information in the sexes. Direct causal links between signal trait expression and physiology represent a novel mechanism that continually maintains the information content of static signal traits.