Male social niche conformance? Effects of manipulated opportunity for extra-pair mating on behavior and hormones of male zebra finches.

Success in sperm competition is an important determinant of male fitness in mating systems with female multiple mating. Thus, sperm competition risk represents a key dimension of the male social environment to which individual males are expected to adaptively adjust their reproductive phenotype. Such adaptive phenotypic adjustment we here refer to as male social niche conformance.

Digest: Sexual selection in a multibrooded songbird: The social pair matters.

Which sources of variance in socially monogamous species offer the largest opportunity for sexual selection? Germain et al. study this question in a double-brooding songbird and find that male reproductive success gained within the social bond stands out as an important source of variance across years and lifetimes.