title: Molecular evolution of X-linked accessory gland proteins in Drosophila pseudoobscura.
abstract: In Drosophila melanogaster and Drosophila simulans, positive Darwinian selection drives high rates of evolution of male reproductive genes, and accessory gland proteins (Acps) in particular. Here, we tested whether 13 X-linked male-specific genes, 4 Acps and 9 non-Acps, are under selective forces in the Drosophila pseudoobscura species group, much as those in the D. melanogaster group. We observed a statistically significant correlation in relative rates of nonsynonymous evolution between the two species groups tested. One Acp examined had a higher rate of nonsynonymous substitution than predicted by a neutral model in both species groups, suggesting its divergence was driven by positive Darwinian selection. To further test for the signature of selection, we examined polymorphism of three Acps within D. pseudoobscura. From this test, no Acp individually bore the signature of positive selection, but the 3 Acps together possessed an excess of nonsynonymous differences between species, relative to polymorphism within species. We conclude that faster evolution of Acps in the D. pseudoobscura group appears to be driven by positive selection, as previously suggested in the D. melanogaster group.
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
authors.forename: L S
authors.initials: LS
authors.lastname: Stevison
authors.forename: B A
authors.initials: BA
authors.lastname: Counterman
authors.forename: M A F
authors.initials: MA
authors.lastname: Noor
mesh_terms: D000818:Animals; D001483:Base Sequence; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D016013:Likelihood Functions; D008800:Mexico; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D012044:Regression Analysis; D012641:Selection, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015206:Southwestern United States; D014960:X Chromosome / Q000235:genetics*
chemical_list: D029721:Drosophila Proteins