MOLECULAR SYSTEMATICS AND ZOOGEOGRAPHY OF FLOWERPIERCERS IN THE DIGLOSSA-BARITULA COMPLEX

Relationships among eight species of flowerpiercers in the genus Diglo ssa (Thraupidae) are addressed using data from allozymes, mtDNA sequen ces, and male plumages. Molecular evolution of the mitochondrial cytoc hrome-b gene in this group parallels what has been reported for other birds. Molecular data reveal high levels of genetic differentiation am ong the taxa studied. There is concordance of evolution among mtDNA se quences, allozymes, and plumages for the three taxa in the Diglossa ba ritula superspecies complex. The pattern of phylogeny in the complex s uggests that plumbea (highlands of southern Central America) is most c losely related to baritula (highlands of northern Central America). Di glossa sittoides (highlands of South America) is the sister taxon to t he baritula/plumbea clade. The pattern of phylogeny and genetic distan ces suggest that divergence of taxa in the baritula superspecies compl ex occurred as the result of both dispersal and vicariance during the Pleistocene.