Multiple paternity, reproductive skew and correlates of male reproductive success in a wild population of the Trinidadian guppy

In most species, males have a higher reproductive potential than females, leading to skewed reproductive success, particularly in mating systems where pre- or postcopulatory sexual selection reinforces inequality in male mating success. We investigated multiple paternity, reproductive skew and correlates of male reproductive success in a wild population of the Trinidadian guppy (Poecilia reticulata). We used nine microsatellite loci to assess the frequency of multiple paternity, number of sires per brood and reproductive skew. Across broods, the frequency of multiple paternity was high with 94% of broods having multiple sires (range: 15), resulting in a reproductive skew of 0.14. Variation in male reproductive success was high (range: 014 offspring per male), suggesting that there is considerable opportunity for sexual selection. Next, we examined correlations between male reproductive success and sexual coloration, sperm velocity and gonopodium length. Relative area of orange, black, iridescent and total coloration, and sperm velocity were not correlated with reproductive success. However, gonopodium length explained 14% of the variation in reproductive success, suggesting that gonopodium length is likely a sexually selected trait. We discuss these findings in the light of other studies that genetically dissect joint-sex parentage and examine correlates of male reproductive success in wild populations