Evaluating the Influence of Environmental Factors on the Rate of Extra-Pair Matings in Tropical and Temperate Populations of the House Wren (Troglodytes Aedon)

Abstract

Considerable variation exists in the rate of extra-pair matings (EPMs) in birds. Environmental variability likely influences EPM rates within species, but the effects of local environmental factors on EPM rates are largely unpredictable. To determine whether broad-scale environmental factors might be better predictors of EPM rates within species, we quantified levels of extra-pair paternity in the house wren (Troglodytes aedon) in four populations spanning a range of latitude, elevation, and primary productivity (measured by actual evapotranspiration rates). Our results indicated an intermediate and variable level of EPM among populations (6 -31% extra-pair young) that was not significantly affected by 3 broad-scale environmental factors. We found no correlation between EPM rate and parental relatedness, sire genetic diversity, or offspring male bias. Overall, we suggest that broad-scale environmental factors likely have weak effects on EPM, and that local-scale factors may be more important drivers of intraspecific EPM rates.