Compositional and quantitative divergence in seminal fluid proteomes of two species exhibiting postmating-prezygotic reproductive isolation

Despite their involvement in critical reproductive processes, male seminal fluid proteins (SFPs) are among the most rapidly evolving genes in the genome of many insects. This rapid divergence may contribute to postmating-prezygotic reproductive isolation and speciation. Most previous comparative studies of SFP evolution have focused on protein sequence divergence alone. However, seminal fluid proteomes may also diverge quantitatively, or in the repertoire of SFPs transferred to females. Although such divergence could have significant impacts on the outcome of reproductive processes, only a few studies have characterized the SFP repertoire and quantitatively compared individual SFPs in populations/species with known PMPZ incompatibilities. Here, we use proteomics to compare the SFP repertoire and quantitatively compare individual SFPs between two species (Drosophila mojavensis and D. arizonae) exhibiting PMPZ isolation. Moreover, we functionally test rapidly evolving SFPs for involvement in reproductive outcomes.