Molecular Systematics and Zoogeography of Flowerpiercers in the Diglossa baritula Complex

Abstract

AnsTRACT.--Relationships among eight species of flowerpiercers in the genus Diglossa (Thraupidae) are addressed using data from allozymes, mtDNA sequences, and male plumages. Molecular evolution of the mitochondrial cytochrome-b gene in this group parallels what has been reported for other birds. Molecular data reveal high levels of genetic differentiation among the taxa studied. There is concordance of evolution among mtDNA sequences, allozymes, and plumages for the three taxa in the Diglossa baritula superspecies complex. The pattern of phylogeny in the complex suggests that plumbea (highlands of southern Central America) is most closely related to baritula (highlands of northern Central America). Diglossa sittoides (highlands of South America) is the sister taxon to the baritula/plumbea dade. The pattern of phylogeny and genetic distances suggest that divergence of taxa in the baritula superspecies complex occurred as the result of both dispersal and vicariance during the Pleistocene. Received 8 July 1993, accepted 25 May 1994. DIGLO$$A FLOWERPIERCERS are high-elevation species restricted to montane regions in the Neotropics (Vuilleumier 1969, A.O.U. 1983, Isler and Isler 1987). In addition, Diglossa are morphologically and behaviorally one of the more divergent lineages of tanagers (Bock 1985,