Selection on X-linked genes during speciation in the Drosophila athabasca complex.
We present the results of a restriction site survey of variation at five loci in Drosophila athabasca, complimenting a previous study of the period locus. There is considerably greater differentiation between the three semispecies of D. athabasca at the period locus and two other X-linked genes (no-on-transient-A and E74A) than at three autosomal genes (Xdh, Adh and RC98). Using a modification of the HKA test, which uses fixed differences between the semispecies and a test based on differences in Fst among loci, we show that the greater differentiation of the X-linked loci compared with the autosomal loci is inconsistent with a neutral model of molecular evolution. We explore several evolutionary scenarios by computer simulation, including differential migration of X and autosomal genes, very low levels of migration among the semispecies, selective-sweeps, and background selection, and conclude that X-linked selective sweeps in at least two of the semispecies are the best explanation for the data. This evidence that natural selection acted on the X-chromosome suggests that another X-linked trait, mating song differences among the semispecies, may have been the target of selection.
Section of Genetics and Development, Cornell University, Ithaca, New York 14853-2703, USA. mford@nwfsc.noaa.gov
M J
MJ
Ford
C F
CF
Aquadro
D000426:Alcohol Dehydrogenase / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D004247:DNA; D004268:DNA-Binding Proteins / Q000235:genetics*; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D005260:Female; D017344:Genes, Insect; D014644:Genetic Variation; D008297:Male; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D015183:Restriction Mapping; D012641:Selection, Genetic; D014157:Transcription Factors; D014960:X Chromosome; D014968:Xanthine Dehydrogenase / Q000235:genetics*
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C060408:Eip74EF protein, Drosophila; C070174:NONA protein, Drosophila; D009687:Nuclear Proteins; D014157:Transcription Factors; D004247:DNA; D000426:Alcohol Dehydrogenase; D014968:Xanthine Dehydrogenase