An Electrophoretic Analysis of Rhagoletis (Diptera: Tephritidae) Phylogeny

Abstract

Berlocher, S. H.1 (Department of Entomology, University of Illinois, Urbana, Illinois 61801), and Guy L. Bush2 (Department of Zoology, University of Texas, Austin, Texas 78712) 1982. An electrophoretic analysis of Rhagoletis (Diptera: Tephritidae) phylogeny. Syst. Zool., 31: 136-155.-Electrophoretic analysis of Rhagoletis (Diptera: Tephritidae) has been performed to gain insight into phylogenetic relationships in the genus, and to determine whether Rhagoletis species have cospeciated with their host plants. The electrophoretic phylogeny differs from both the conventional classification and the assumed phylogeny of the host plants. Most of the changes suggested in the conventional classification are compatible with morphological data. The differences in the phylogenies of Rhagoletis and its host plants are not, however, likely to be resolved by further systematic analysis of the host plants. In addition to these topics, we also discuss the electrophoretic phylogeny with respect to the biogeography of the genus. [Electrophoresis; phylogeny; genetic distance; coevolution; Rhagoletis; Tephritidae.] The fruit flies of the genus Rhagoletis Loew are common orchard pests in many parts of the world, since they feed as larvae in a wide variety of fruits (Boller and Prokopy, 1975). The genus is better known to evolutionary biology as a key exhibit in debate over the existence of sympatric speciation (Bush, 1966, 1969, 1975a, b; Mayr, 1963, 1970, 1978; Futuyma and Mayer, 1980). In a less wellknown context, these flies can contribute data to the renewed argument about the importance and interpretation of phylogenetic coevolution between parasites and their hosts (Brooks, 1979, 1980a, b; Holmes and Price, 1980). In this paper we estimate the phylogeny of Rhagoletis species using electrophoretic data. We answer three questions: 1) What phylogeny do the electrophoretic data support? 2) Is the electrophoretic phylogeny congruent with the existing systematics of the genus? 3) Is the electrophoretic phylogeny congruent with the systematics of the host plants of the flies? We also discuss the 1 This work was begun as part of the author's doctoral research in the Department of Zoology, University of Texas, Austin, Texas. 2 Present address: Department of Zoology, Michigan State University, East Lansing, Michigan 48824. phylogeny of the genus with respect to its biogeography.