Mitochondrial Perspective on the Phylogenetic Relationships of the Parula Wood-warblers

Abstract

Studies of intraspecific genetic variation in Neotropical resident birds have frequently revealed a high degree of phylogeographic differentiation (e.g. Capparella 1988, Hackett and Rosenberg 1990, Peterson et al. 1992, Bates and Zink 1994, Hackett 1996). That trend suggests tropical bird species are particularly likely to be subdivided geographically and that their constituent lineages tend to be evolutionarily old. Only a few counterexamples have been reported in which molecular surveys of Neotropical avian species did not reveal phylogeographic structure. Brawn et al. (1996) found no differences in mtDNA RFLP haplotypes between populations of three passerine species on the Perlas Islands in the Bay of Panama and conspecific populations on the nearby mainland. However, the geographic distances (<100 km) and putative period of genetic isolation (<10,000 years) in that system were both short. Gutierrez (1994) found similarly low mtDNA divergence in Oilbirds (Steatornis caripensis) from colonies 400 km apart in northern Venezuela. On a broader geographic scale, Brumfield and Capparella (1996) observed considerable protein divergence between Central and South American House Wrens (Troglodytes aedon), but found little differentiation among locations along a 7,000 km transect from Panama to Tierra del Fuego. Here we explore the magnitude of mtDNA differentiation among geographically distant populations of the Tropical Parula (Parula pitiayumi), and we use mtDNA sequences to explore the relationship of R pitiayumi to the three other species currently placed in Parula (AOU 1998). Parula pitiayumi has a breeding distribution that extends from Northern Mexico south through much of South America and has been divided into 14 subspecies (Lowery and Monroe 1968). Based on its broad geographic distribution and high phenotypic diversity, our a priori expectation was that R pitiayumi would display evidence of