Phylogenetic relationships and macro-evolutionary patterns within the Drosophila tripunctata "radiation" (Diptera: Drosophilidae)

Abstract

Despite previous efforts, the evolutionary history of the immigrans-tripunctata clade remains obscure in part due to its hypothesized origin through a rapid radiation. We performed a supermatrix analysis (3,243 base pairs) coupled with richness patterns, environmental phylogenetic signal and radiation tests in order to address phylogenetic relationships and macro-evolutionary hypotheses within this complex group of species. We propose a well-supported evolutionary scenario for the immigrans-tripunctata clade species, in which the tripunctata "radiation" was monophyletic and subdivided into three main lineages: the first including D. pallidipennis (pallidipennis group) imbedded among members of the tripunctata group; the second clustering the cardini and guarani groups; and the third grouping representatives from the tripunctata, calloptera and guaramunu groups. Therefore, we hypothesize that the tripunctata group encompasses a diphyletic taxon, with one clade including the pallidipennis group and the other showing a close affinity to the calloptera and guaramunu groups. Our results also suggest that niche evolution seems to have played a central role in the evolutionary history of the tripunctata species "radiation" allowing effective dispersion and diversification in the Neotropics, possibly in a southwards direction. Although the data as a whole support the notion that this occurred through rapid and successive speciation events, the radiation hypothesis remains to be further corroborated.