Get access

EXTRA-PAIR PATERNITY AND THE VARIANCE IN MALE FITNESS IN SONG SPARROWS (MELOSPIZA MELODIA)

Authors

  • Christophe Lebigre,

    1. Institute of Biological and Environmental Sciences, School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, United Kingdom
    Search for more papers by this author
  • Peter Arcese,

    1. Centre for Applied Conservation Research, Forest Sciences Centre, 2424 Main Mall, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
    Search for more papers by this author
  • Rebecca J. Sardell,

    1. Institute of Biological and Environmental Sciences, School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, United Kingdom
    Search for more papers by this author
  • Lukas F. Keller,

    1. Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
    Search for more papers by this author
  • Jane M. Reid

    1. Institute of Biological and Environmental Sciences, School of Biological Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen, AB24 2TZ, United Kingdom
    2. E-mail: jane.reid@abdn.ac.uk
    Search for more papers by this author

Abstract

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.

Get access to the full text of this article

Ancillary