MOLECULAR POPULATION-GENETICS OF THE ALCOHOL-DEHYDROGENASE LOCUS IN THE HAWAIIAN DROSOPHILID DROSOPHILA-MIMICA

Sequence variation among 10 alleles of the alcohol dehydrogenase (Adh) gene of the Hawaiian drosophilid D. mimica was analyzed with referenc e to the evolutionary history of the Hawaiian subgroup as well as to l evels and patterns of polymorphism of the Adh gene in continental dros ophilid species. The Adh gene of D. mimica is less polymorphic than th at of other drosophilid species, and no replacement substitutions were found. Statistical analyses of the Adh alleles suggested the action o f balancing selection and revealed significant linkage disequilibrium among three of the variable sites. The effective population size was e stimated to be only slightly smaller than that of continental species and, surprisingly, on the same order of magnitude as the actual size.