Projects

The Warbler Tree of Life

We are using DNA sequences to determine the evolutionary tree for the 100+ species of wood-warblers (family Parulidae). This project is funded by the National Science Foundation and is embedded within a broader project on the evolutionary “Tree of Life” of the Emberizines, a group of 800+ bird species that includes familiar groups such as warblers, tanagers, orioles, blackbirds, sparrows, cardinals, as well as less familiar (and evolutionarily more mysterious) birds such as the Yellow-throated Chat, Wrenthrush, Rosy Thrush-tanager, and Bobolink.
	This larger project is a collaboration among researchers from many institutions, including the Cornell Laboratory of Ornithology (Irby Lovette), Bell Museum of the University of Minnesota (Scott Lanyon and Keith Barker), San Diego State University (Kevin Burns), and Barrick Museum of the University of Nevada-Las Vegas (John Klicka). Each of these research groups is responsible for providing DNA information on one subgroup within the larger Emberizine radiation.
By pooling our information and resources, we have the power to generate a complete evolutionary tree on a scale never before attempted for birds. The foremost goal of this project is to produce an evolutionary tree that includes all species within the Emberizinae. Obtaining DNA samples from some of these species is difficult, but many museums and institutions have generously loaned us samples from their collections.
	A well defined evolutionary tree for this group will have many uses. One of the most direct is in clarifying our understanding of evolutionary relationships. For example, our research has already shown that a number of species of birds long considered to be warblers are not closely related to the “true” warblers. Once all of the data are in, this type of information will help us revise Emberizine taxonomy (latin names) so that it accurately reflects evolutionary relationships. This process will have little impact on common (English) names.
A second use of these trees is in conducting other types of evolutionary analysis. One example: a long-standing hypothesis states that birds that nest on the ground tend to have drab, cryptic plumage to avoid attracting predators. It is tempting to study this posssibility just by listing drab versus colorful species and seeing which group tends to nest on the ground, but this approach has a major flaw in that it ignores similarities that arise from species simply being closely related. In other words, two species might both be drab and have similar nests only because their recent ancestor had these traits, not owing to ongoing natural selection by predators. Testing this type of evolutionary hypothesis therefore requires a good evolutionary tree so that you can see when the various traits actually changed over the course of evolution. If a large number of species independently evolved ground nesting and at the same time indepdently evolved drab plumage, it would s! uggest that the two traits are strongly associated. Papers listed on our publications page include a number of products from our research on warbler relationships. back to top