Meeting Abstract
14.5 Tuesday, Jan. 4 Hormone levels predict individual differences in reproductive success in a passerine bird OUYANG, Jenny Q*; SHARP, Peter; DAWSON, Alistair; HAU, Michaela; Princeton University, Princeton, NJ; University of Edinburgh, U.K; Centre for Ecology and Hydrology, Edinburgh, UK; Max Planck Institute for Ornithology, Radolfzell, Germany jqouyang@gmail.com
Hormones mediate major physiological and behavioural components of the reproductive phenotype of individuals. To understand basic evolutionary processes in the hormonal regulation of reproductive traits we need to know whether, and during which reproductive phases, individual variation in hormone concentrations relates to fitness in natural populations. We quantified circulating concentrations of prolactin and corticosterone along with parental behaviour and reproductive success during the pre-breeding and chick-rearing stages in free-living house sparrows, Passer domesticus. In general, hormone concentrations were correlated between members of a pair. Prolactin and baseline corticosterone concentrations during pre-breeding in females, and pre-breeding prolactin concentrations in males predicted total number of fledglings. When correcting for the strong effect of lay date on total fledgling number, pre-breeding baseline corticosterone remained a significant predictor of reproductive success in females. During the breeding season, nestling provisioning rates of both sexes varied negatively with stress-induced corticosterone levels. Lastly, individuals of both sexes with low baseline corticosterone before and high baseline corticosterone during breeding raised the most offspring, suggesting that up-regulation of this trait contributes to reproductive success. Thus hormone concentrations both before and during breeding as well as their seasonal dynamics predict reproductive success, suggesting that individual variation in absolute concentrations and in plasticity is functionally significant and, if heritable, may be a target of selection.
