Data from: Extra-pair paternity and the variance in male fitness in song sparrows (Melospiza melodia)

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 and extra-pair reproductive success 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 within- and extra-pair reproductive success and large variance in within-pair reproductive success 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.

Usage notes summary data ARS Data describing variation in male annual reproductive success summary data LRS Data describing variation in male lifetime reproductive success and fitness