Nucleotide Variation in the Egfr Locus of Drosophila melanogaster

As part of an effort to dissect quantitative trait locus effects to the nucleotide level, association was assessed between 238 single-nucleotide and 20 indel polymorphisms spread over 11 kb of the Drosophila melanogaster Egfr locus and nine relative warp measures of wing shape. One SNP in a conserved potential regulatory site for a GAGA factor in the promoter of alternate first exon 2 approaches conservative experimentwise significance (P < 0.00003) in the sample of 207 lines for association with the location of the crossveins in the central region of the wing. Several other sites indicate marginal association with one or more other aspects of shape. No strong effects of sex or population of origin were detected with measures of shape, but two different sites were strongly associated with overall wing size in interaction with these fixed factors. Whole-gene sequencing in very large samples, rather than selective genotyping, would appear to be the only strategy likely to be successful for detecting subtle associations in species with high polymorphism and little haplotype structure. However, these features severely limit the ability of linkage disequilibrium mapping in Drosophila to resolve quantitative effects to single nucleotides