Microcomplement fixation studies on the evolution of alpha-glycerophosphate dehydrogenase within the genus Drosophila

Antisera were prepared against purified alpha-glycerophosphate dehydrogenase (EC 1.1.1.8) (alphaGPDH) from Drosophila melanogaster, D. virilis, and D. busckii. The immunological distances between the enzymes from the 3 species and those from 31 additional drosophilid species agree in general with the accepted phylogeny of the genus. These data permit an estimate that the subgenus Sophophora diverged 52 million years ago from the line leading to the subgenus Drosophila. The antiserum against melanogaster alphaGPDH was capable of distinguishing allelic variants of alphaGPDH. On the basis of presumed single amino acid substitutions, no drosophilid alphaGPDH tested differed from the melanogaster enzyme by more than eight or nine substitutions. The study was extended to include representatives of six other dipteran families. The immunological distances between alphaGPDH from Drosophila and alphaGPDH from these dipterans were reasonably consistent with a phylogeny of the order Diptera established by more conventional means. The unit evolutionary period of this enzyme was estimated to be 18 million years.