title: Sexual selection and the adaptive evolution of PKDREJ protein in primates and rodents.
abstract: PKDREJ is a testis-specific protein thought to be located on the sperm surface. Functional studies in the mouse revealed that loss of PKDREJ has effects on sperm transport and the ability to undergo an induced acrosome reaction. Thus, PKDREJ has been considered a potential target of post-copulatory sexual selection in the form of sperm competition. Proteins involved in reproductive processes often show accelerated evolution. In many cases, this rapid divergence is promoted by positive selection which may be driven, at least in part, by post-copulatory sexual selection. We analysed the evolution of the PKDREJ protein in primates and rodents and assessed whether PKDREJ divergence is associated with testes mass relative to body mass, which is a reliable proxy of sperm competition levels. Evidence of an association between the evolutionary rate of the PKDREJ gene and testes mass relative to body mass was not found in primates. Among rodents, evidence of positive selection was detected in the Pkdrej gene in the family Cricetidae but not in Muridae. We then assessed whether Pkdrej divergence is associated with episodes of sperm competition in these families. We detected a positive significant correlation between the evolutionary rates of Pkdrej and testes mass relative to body mass in cricetids. These findings constitute the first evidence of post-copulatory sexual selection influencing the evolution of a protein that participates in the mechanisms regulating sperm transport and the acrosome reaction, strongly suggesting that positive selection may act on these fertilization steps, leading to advantages in situations of sperm competition.
authors.affiliation: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), 28006, Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Vicens
authors.affiliation: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), 28006, Madrid, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Gómez Montoto
authors.affiliation: Departamento de Biología Medioambiental, Centro de Investigaciones Biológicas (CSIC), 28040, Madrid, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Couso-Ferrer
authors.affiliation: Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
authors.forename: Keith A
authors.initials: KA
authors.lastname: Sutton
authors.affiliation: Reproductive Ecology and Biology Group, Museo Nacional de Ciencias Naturales (CSIC), 28006, Madrid, Spain roldane@mncn.csic.es.
authors.forename: Eduardo R S
authors.initials: ER
authors.lastname: Roldan
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004901:Erythrocebus patas; D006071:Gorilla gorilla; D006801:Humans; D008253:Macaca mulatta; D008254:Macaca nemestrina; D008297:Male; D019974:Pan paniscus; D002679:Pan troglodytes; D011148:Pongo pygmaeus; D011323:Primates / Q000145:classification / Q000235:genetics / Q000502:physiology*; D012377:Rodentia / Q000145:classification / Q000235:genetics / Q000502:physiology*; D013094:Spermatozoa / Q000378:metabolism / Q000502:physiology
keywords: PKDREJ; positive selection; primates; rodents; sperm competition