title: Sperm Bindin Divergence under Sexual Selection and Concerted Evolution in Sea Stars.
abstract: Selection associated with competition among males or sexual conflict between mates can create positive selection for high rates of molecular evolution of gamete recognition genes and lead to reproductive isolation between species. We analyzed coding sequence and repetitive domain variation in the gene encoding the sperm acrosomal protein bindin in 13 diverse sea star species. We found that bindin has a conserved coding sequence domain structure in all 13 species, with several repeated motifs in a large central region that is similar among all sea stars in organization but highly divergent among genera in nucleotide and predicted amino acid sequence. More bindin codons and lineages showed positive selection for high relative rates of amino acid substitution in genera with gonochoric outcrossing adults (and greater expected strength of sexual selection) than in selfing hermaphrodites. That difference is consistent with the expectation that selfing (a highly derived mating system) may moderate the strength of sexual selection and limit the accumulation of bindin amino acid differences. The results implicate both positive selection on single codons and concerted evolution within the repetitive region in bindin divergence, and suggest that both single amino acid differences and repeat differences may affect sperm-egg binding and reproductive compatibility.
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
authors.forename: Susana
authors.initials: S
authors.lastname: Patiño
authors.affiliation: Department of Biology, Kwantlen Polytechnic University, Surrey, BC, Canada.
authors.forename: Carson C
authors.initials: CC
authors.lastname: Keever
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Sunday
authors.affiliation: School of Biological Sciences, University of Queensland, Brisbane, QLD, Australia.
authors.forename: Iva
authors.initials: I
authors.lastname: Popovic
authors.affiliation: Schools of Medical and Biological Sciences, University of Sydney, Sydney, NSW, Australia.
authors.forename: Maria
authors.initials: M
authors.lastname: Byrne
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada mwhart@sfu.ca.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Hart
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D005075:Biological Evolution; D003062:Codon; D019143:Evolution, Molecular; D005260:Female; D005306:Fertilization; D008297:Male; D052586:Mating Preference, Animal; D010802:Phylogeny; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism*; D060047:Reproductive Isolation; D013045:Species Specificity; D013094:Spermatozoa / Q000378:metabolism / Q000502:physiology*; D013215:Starfish / Q000235:genetics* / Q000378:metabolism
chemical_list: D003062:Codon; D011956:Receptors, Cell Surface; C035027:egg surface sperm receptor
keywords: fertilization; gamete recognition; positive selection; sexual selection; speciation.