Excess of amino acid substitutions relative to polymorphism between X-linked duplications in Drosophila melanogaster.
We have obtained sequence polymorphism data from 13 genes belonging to 5 gene families in Drosophila melanogaster where the K(a)/K(s) between copies is greater than 1. Twelve of these 13 loci are X-linked. In general, there is evidence of purifying selection in all families, as inferred both from levels of silent and replacement variation and insertion/deletion variation, suggesting that the loci are likely functional. Shared polymorphisms indicative of gene conversion between paralogs are rare among the X-linked families, in contrast to available data from autosomal duplicates. McDonald-Kreitman tests between duplicates reveal an excess of amino-acid fixations between copies in the X-linked families, suggesting that the divergence between these loci was driven by positive selection. In contrast, available data from autosomal duplicates show a deficit of fixations, consistent with gene conversion being a strong homogenizing force.
Department of Ecology and Evolution and the Committee on Genetiecs, University of Chicago, USA.
Kevin
K
Thornton
Manyuan
M
Long
D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D029721:Drosophila Proteins / Q000235:genetics; D004331:Drosophila melanogaster / Q000235:genetics*; D020440:Gene Duplication; D020131:Genes, Duplicate; D017344:Genes, Insect; D011110:Polymorphism, Genetic; D012641:Selection, Genetic; D014960:X Chromosome / Q000235:genetics*
D029721:Drosophila Proteins