Meeting Abstract

114.7  Tuesday, Jan. 7 11:45  Individual physiological plasticity in an avian range expansion MARTIN, LB*; LIEBL, AL; Department of Integrative Biology. University of South Florida; Centre for Ecology and Conservation, School of Biosciences, University of Exeter lbmartin@usf.edu

The mechanisms that enable animals to colonize new areas are little known, but growing evidence indicates that the regulation of stress hormones is important. Stress hormones probably influence invasions because they are pleiotropic, enabling organisms to adjust their phenotypes cohesively contingent on environmental context. Here, we asked whether plasticity in the regulation of one stress hormone, the steroid corticosterone, was related to colonization success in one of the world’s most successful avian invaders, the house sparrow (Passer domesticus). We studied Kenyan house sparrows, as the species was introduced there around 1950 and has since expanded westward. Previous work in this system revealed that younger populations released more corticosterone during a restraint stressor than older populations. Our first goal was to discern whether such population differences were fixed or plastic in adulthood; our second goal was to determine whether population-level plasticity was consistent or heterogeneous among individuals within populations. The latter goal was motivated by recent discoveries that individual plasticity is ecologically important but sometimes constrained by personality. We found that both baseline and stress-induced corticosterone measures were plastic at the population level; moreover, populations differed in plasticity of baseline corticosterone. We found evidence for corticosterone regulatory personalities too, but we found little evidence for covariation (constraint) among regulatory elements. Altogether, our data suggest that the colonization success of Kenyan house sparrows might be due to stress hormone regulatory plasticity.