Molecular systematics of Drosophila. A. Tatarenkov , F.J. Ayala. Department of Ecology & Evolutionary Biology, University of California, Irvine, CA.

   Two genes, amd and Ddc, were sequenced in more than 50 species representative of Drosophila subgenera and species-groups of interest. These genes, separately and in combination with available data for Adh and Sod, resolve most of the previously unsettled phylogenetic relationships between species groups and subgenera, as well as some taxa previously considered as genera, but here treated as subgenera, namely Zaprionus, Samoaia, Liodrosophila, and Scaptomyza, which occupy more derived positions on the tree, relative to the subgenus Sophophora (which includes D. melanogaster). Using Scaptodrosophila lebanonensis as outgroup, we show that the subgenus Sophophora is an early offshoot within the genus Drosophila. Among groups that are derived relative to Sophophora, Zaprionus is the basal branch. Hawaiian Drosophila and Scaptomyza are monophyletic, and a sister-clade to the virilis-repleta lineage. Of the 12 species groups of the virilis-repleta radiation (sensu Throckmorton, 1975), 11 groups form a monophyletic cluster. One group, tumiditarsus, seemingly does not belong to the radiation; its placement within the Drosophilinae remains uncertain. Among the 11 groups of the lineage, D. polychaeta is the earliest splitting branch. The species groups quinaria, testacea, tripunctata, and funebris (all in the subgenus Drosophila) are closely related, and form a monophyletic group with immigrans (subgenus Drosophila) and the genus Samoaia. The positions of Hirtodrosophila, Liodrosophila, and Dorsilopha are not fully resolved.