Meeting Abstract

28.2  Saturday, Jan. 4 13:45  Oxidative Costs of Reproduction and the Evolution of Cooperative Breeding GUINDRE-PARKER, S.*; RUBENSTEIN, D.R.; Columbia University, NYC; Columbia University, NYC slg2154@columbia.edu

For cooperative breeders where more than two individuals care for young, high costs of parental care may contribute to the evolution of this social behavior. This hypothesis has gone largely untested for two reasons. First, the physiological mechanisms underlying reproductive costs remain a mystery, and second, the reproductive costs for cooperatively breeding species have not been studied in a comparative context. Here we compared the costs of reproduction in two closely related species of African starlings that differ in their social behavior: the cooperatively breeding superb starling (Lamprotornis superbus) and the non-cooperatively breeding greater blue-eared glossy starling (Lamprotornis chalybaeus). To determine if physiological costs associated with reproduction underlie differences in sociality, we assessed (1) the potential of oxidative stress— an imbalance between reactive oxygen species and antioxidants—as a currency of the costs of reproduction and (2) the physiological differences between species/individuals of different breeding roles. We found that oxidative stress is representative of behavioral workload, suggesting that oxidative balance is an adequate measure of both breeding effort and the costs of reproduction. Moreover, the change in oxidative balance differed by species and breeding role, as social fathers of the non-cooperative species increased in oxidative stress to a greater extent from early to late breeding. Thus, having helpers at the nest may reduce the costs—as measured by oxidative balance—of paternal care and ultimately help drive the evolution of cooperative breeding behavior. For species inhabiting harsh and unpredictable environments, the differential costs of breeding may therefore explain why some species breed cooperatively while others living in the same environment do not.