Phylogenetic resolution of North American Rhagoletis (Diptera: Tephritidae) species groups

Flies in the genus Rhagoletis (Diptera: Tephritidae) are economically important fruit pests, which serve as models for studying modes of speciation and coevolutionary relationships with their hymenopteran parasitoids. Nearctic Rhagoletis belong to one of five species groups (pomonella, tabellaria, cingulata, suavis, and ribicola), plus R. juniperina Marcovitch and R. fausta (Osten Stacken).  The phylogenetic relationships of Nearctic Rhagoletis remain unresolved despite analyses based on morphology, allozymes, and mitochondrial DNA. Also, monophyly of Nearctic Rhagoletis is in question; earlier data based on mitochondrial COII showed that monophyly of Nearctic Rhagoletis is disrupted by two Palearctic taxa, R. batava Hering and R. flavigenualis Hering. Thus, the main goals of this project are to circumscribe the monophyletic group containing the Nearctic species and to resolve phylogenetic relationships within it. We make phylogenetic inferences was based on DNA sequences from mitochondrial COI, and the nuclear 28S, CAD and period genes. Analysis of the combined dataset shows monophyly of the five Nearctic species groups, with the pomonella group sister to the tabellaria group. The Palearctic Elaeagnacee-infesting R. batava is placed sister to the five species groups, followed by a clade consisting of R. juniperina and the Palearctic juniper-infesting R. flavigenualis , and then R. fausta.  Our data indicate a close relationship of juniper-infesting Rhagoletis, and the close relationships of Palearctic taxa to Nearctic taxa infesting similar host plants may have implications for the phylogeography of the genus. Whether the observed phylogenetic pattern resulted from adaptive radiation(s) remains to be tested.