Molecular population genetics of female-expressed mating-induced serine proteases in Drosophila melanogaster

Population genetic analyses have shown that directional selection causes amino acid substitution in several seminal fluid proteins (Acps) and that in general, Acps tend to diverge rapidly. If rapid, adaptive divergence of such male reproduction-related genes is driven by sexual conflict, we might also expect to observe rapid, adaptive evolution in female reproduction-related genes, especially those mediating conflicts between the sexes. Female expressed genes differentially expressed shortly after mating were recently identified using whole genome expression micro-arrays. Such genes may play roles in storing sperm and mediating effects of seminal fluid proteins. Here, we report the results of a molecular population genetic survey from five female reproductive tract expressed serine proteases that show increased transcription shortly after mating. These genes are evolving rapidly, in some cases under directional selection, consistent with models of conflict.