A comprehensive study of genic variation in natural populations of Drosophila melanogaster. VI. Patterns and processes of genic divergence between D. melanogaster and its sibling species, Drosophila simulans.

We present here an extensive set of data on allelic differences between homologous proteins of Drosophila melanogaster and its sibling species, Drosophila simulans, obtained by nondenaturing one-dimensional, and denaturing two-dimensional gel electrophoresis. The data suggest that, for these two species, (1) approximately 10% of protein-coding loci have no alleles in common in our sample, (2) the extent of genic variation at a locus (mean heterozygosity) within a species is not correlated with the extent of divergence (Nei's genetic distance) at that locus between species, and (3) significant heterogeneity of divergence rates exists for different structural/functional classes of loci. These results are discussed in the context of the dynamics of genetic variation within and between species.