Patterns of selection on synonymous and nonsynonymous variants in Drosophila miranda.
We have investigated patterns of within-species polymorphism and between-species divergence for synonymous and nonsynonymous variants at a set of autosomal and X-linked loci of Drosophila miranda. D. pseudoobscura and D. affinis were used for the between-species comparisons. The results suggest the action of purifying selection on nonsynonymous, polymorphic variants. Among synonymous polymorphisms, there is a significant excess of synonymous mutations from preferred to unpreferred codons and of GC to AT mutations. There was no excess of GC to AT mutations among polymorphisms at noncoding sites. This suggests that selection is acting to maintain the use of preferred codons. Indirect evidence suggests that biased gene conversion in favor of GC base pairs may also be operating. The joint intensity of selection and biased gene conversion, in terms of the product of effective population size and the sum of the selection and conversion coefficients, was estimated to be approximately 0.65.
Bartolomé
Carolina
C
Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, UK. cbhusson@usc.es
Maside
Xulio
X
Yi
Soojin
S
Grant
Anna L
AL
Charlesworth
Brian
B
D000818:Animals; D001482:Base Composition; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000235:genetics*; D005091:Exons; D014644:Genetic Variation; D016133:Polymerase Chain Reaction; D012641:Selection, Genetic; D014960:X Chromosome
D029721:Drosophila Proteins; D004247:DNA