MOLECULAR ARMS RACE. “Molecular evolutionary patterns support this role for sexual conflict, as the family of SFP genes (comprising at least 140 members) are rapidly evolving at the sequence level. The female side of this putative arms race, involving primarily proteases expressed in the reproductive tract, also shows evidence of rapid evolution and a signature of strong selection.” (SFPs = male seminal fluid proteins).
http://onlinelibrary.wiley.com/doi/10.1111/jeb.12763/full