EXTRA-PAIR PATERNITY AND THE VARIANCE IN MALE FITNESS IN SONG SPARROWS (MELOSPIZA MELODIA)
Article first published online: 21 MAY 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 66, Issue 10, pages 3111–3129, October 2012
How to Cite
Lebigre, C., Arcese, P., Sardell, R. J., Keller, L. F. and Reid, J. M. (2012), EXTRA-PAIR PATERNITY AND THE VARIANCE IN MALE FITNESS IN SONG SPARROWS (MELOSPIZA MELODIA). Evolution, 66: 3111–3129. doi: 10.1111/j.1558-5646.2012.01677.x
- Issue published online: 1 OCT 2012
- Article first published online: 21 MAY 2012
- Accepted manuscript online: 21 APR 2012 12:34PM EST
- Received July 12, 2011, Accepted April 2, 2012, Data Archived: Dryad doi:10.5061/dryad.6sb403hc
- lifetime reproductive success;
- opportunity for selection;
- sexual selection;
- variance in fitness
The variance in fitness across population members can influence major evolutionary processes. In socially monogamous but genetically polygynandrous species, extra-pair paternity (EPP) is widely hypothesized to increase the variance in male fitness compared to that arising given the socially monogamous mating system. This hypothesis has not been definitively tested because comprehensive data describing males’ apparent (social) and realized (genetic) fitness have been lacking. We used 16 years of comprehensive social and genetic paternity data for an entire free-living song sparrow (Melospiza melodia) population to quantify and compare variances in male apparent and realized fitness, and to quantify the contribution of the variances in within-pair reproductive success (WPRS) and extra-pair reproductive success (EPRS) and their covariance to the variance in realized fitness. Overall, EPP increased the variance in male fitness by only 0–27% across different fitness and variance measures. This relatively small effect reflected the presence of socially unpaired males with zero apparent and low realized fitness, small covariance between WPRS and EPRS, and large variance in WPRS that was relatively unaffected by EPP. Therefore, although EPP altered individual males’ contributions to future generations, its impact on population-level parameters such as the opportunity for selection and effective population size was limited.