title: Mating systems and protein-protein interactions determine evolutionary rates of primate sperm proteins.
abstract: To assess the relative impact of functional constraint and post-mating sexual selection on sequence evolution of reproductive proteins, we examined 169 primate sperm proteins. In order to recognize potential genome-wide trends, we additionally analysed a sample of altogether 318 non-reproductive (brain and postsynaptic) proteins. Based on cDNAs of eight primate species (Anthropoidea), we observed that pre-mating sperm proteins engaged in sperm composition and assembly show significantly lower incidence of site-specific positive selection and overall lower non-synonymous to synonymous substitution rates (dN/dS) across sites as compared with post-mating sperm proteins involved in capacitation, hyperactivation, acrosome reaction and fertilization. Moreover, database screening revealed overall more intracellular protein interaction partners in pre-mating than in post-mating sperm proteins. Finally, post-mating sperm proteins evolved at significantly higher evolutionary rates than pre-mating sperm and non-reproductive proteins on the branches to multi-male breeding species, while no such increase was observed on the branches to unimale and monogamous species. We conclude that less protein-protein interactions of post-mating sperm proteins account for lowered functional constraint, allowing for stronger impact of post-mating sexual selection, while the opposite holds true for pre-mating sperm proteins. This pattern is particularly strong in multi-male breeding species showing high female promiscuity.
authors.affiliation: Institute of Anthropology, University of Mainz, , Anselm-Franz-von-Bentzel-Weg 7, 55099 Mainz, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Schumacher
authors.forename: David
authors.initials: D
authors.lastname: Rosenkranz
authors.forename: Holger
authors.initials: H
authors.lastname: Herlyn
mesh_terms: D000818:Animals; D018076:DNA, Complementary / Q000737:chemistry; D019143:Evolution, Molecular; D000882:Haplorhini / Q000235:genetics*; D008297:Male; D052586:Mating Preference, Animal; D054730:Protein Interaction Domains and Motifs; D017422:Sequence Analysis, DNA; D012726:Sexual Behavior, Animal; D013094:Spermatozoa / Q000378:metabolism*; D013737:Testis / Q000378:metabolism
chemical_list: D018076:DNA, Complementary
keywords: brain proteins; functional constraint; mating system; sexual selection; sperm competition; sperm proteins