Restriction-map variation in natural populations of Drosophila melanogaster: white-locus region.

Restriction-map variation among 38 chromosomes collected from natural populations from around the world was surveyed using probes for a 45-kb region containing and surrounding the white locus. Insertion and deletion variation was more common in the regions flanking the white transcriptional unit, and restriction-site polymorphism appears to be most common 5' of the white locus. The frequencies of individual large insertions (suspected transposable elements) were low, although 37% of the chromosomes had at least one insertion in the white-locus region. The estimated level of nucleotide heterozygosity over the whole region was 0.012. There was little linkage disequilibrium among the polymorphic sites. In contrast to earlier reports of the variation in other regions of the Drosophila melanogaster genome, there seemed to be less linkage disequilibrium and perhaps more nucleotide polymorphism.