Evidence for selection at the fused locus of Drosophila virilis.
The genomic DNA sequence of a 2.4-kb region of the X-linked developmental gene fused was determined in 15 Drosophila virilis strains. One common replacement polymorphism is observed, where a negatively charged aspartic amino acid is replaced by the noncharged amino acid alanine. This replacement variant is located within the serine/threonine kinase domain of the fused gene and is present in approximately 50% of the sequences in our sample. Significant linkage disequilibrium is detected around this replacement site, although the fused gene is located in a region of the D. virilis X chromosome that seems to experience normal levels of recombination. In a 600-bp region around the replacement site, all eight alanine sequences are identical; of the six aspartic acid sequences, three are also identical. The occurrence of little or no variation within the aspartic acid and alanine haplotypes, coupled with the presence of several differences between them, is very unlikely under the usual equilibrium neutral model. Our results suggest that the fused alanine haplotypes have recently increased in frequency in the D. virilis population.
Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom. j.vieira@ed.ac.uk
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Vieira
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Charlesworth
D000409:Alanine / Q000235:genetics; D000483:Alleles; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics; D001483:Base Sequence; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins; D005787:Gene Frequency; D015810:Linkage Disequilibrium; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics*; D017434:Protein Structure, Tertiary; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014960:X Chromosome / Q000235:genetics
D029721:Drosophila Proteins; D001224:Aspartic Acid; C085770:fu protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D000409:Alanine