The role of reproductive conflicts in genetic, phenotypic, and species divergence

ABSTRACT Connecting natural selection of phenotypes with molecular evolution is one of the central goals of evolutionary biology. Using phylogenetic methods, I tested the hypothesis that reproductive conflicts related to sperm competition drive the adaptive molecular evolution of primate reproductive proteins. To control for potential empirical or statistical biases in the data, I compared results from 22 ‘housekeeping’ proteins, to those of 28 reproductive proteins. Positive correlations between sperm competition and adaptive molecular evolution were significantly greater amongst reproductive proteins than amongst control group proteins. Reproductive proteins implicated in seminal coagulation and sperm-egg interactions, including two female-expressed proteins, had particularly high correlation coefficients. These results suggest that inter- as well as intra-sexual reproductive conflicts generate adaptive divergence in reproductive proteins. The nature of molecular interactions may mean that reproductive conflicts between males and females at this level are particularly likely to lead to the reproductive isolation of allopatric populations.