title: Evolution of 2 reproductive proteins, ZP3 and PKDREJ, in cetaceans.
abstract: The rapid evolution of proteins involved in reproduction has been documented in several animal taxa. This is thought to be the result of forces involved in sexual selection and is expected to be particularly strong in promiscuous mating systems. In this study, a range of cetacean species were used to analyze the patterns of evolution in 2 reproductive proteins involved in fertilization: the zona pellucida 3 (ZP3), present in the egg coat, and PKDREJ, localized in the sperm head. We targeted exons 6 and 7 of ZP3 and a part of the REJ domain in PKDREJ for a total of 958 bp in 18 species. We found very low levels of amino acid sequence divergence in both proteins, a very weak signal of positive selection in ZP3 and no signal in PKDREJ. These results were consistent with previous reports of a slow rate of molecular evolution in cetaceans but unexpected due to the existence of promiscuous mating systems in these species. The results raise questions about the evolution of reproductive isolation and species recognition in whales and dolphins.
authors.affiliation: Centro de Biologia Ambiental, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, Lisbon, Portugal. aramaral@fc.ul.pt
authors.forename: Ana R
authors.initials: AR
authors.lastname: Amaral
authors.forename: Luciana M
authors.initials: LM
authors.lastname: Möller
authors.forename: Luciano B
authors.initials: LB
authors.lastname: Beheregaray
authors.forename: M Manuela
authors.initials: MM
authors.lastname: Coelho
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D002591:Cetacea / Q000145:classification* / Q000235:genetics*; D004527:Egg Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D005091:Exons; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D011956:Receptors, Cell Surface / Q000235:genetics*; D013084:Sperm-Ovum Interactions / Q000235:genetics
chemical_list: D004527:Egg Proteins; D011956:Receptors, Cell Surface; C035027:egg surface sperm receptor