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2005
LSU-HHMI Summer Undergraduate Research Program |
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Katherine Faust and Robb Brumfield, Biological Sciences and Museum of Natural Sciences
Genetic structure of a hybrid zone between two species of Jamaican Streamertail Hummingbirds
When the geographical distributions of two closely related species come into contact, one potential outcome is the formation of a stable hybrid zone, a narrow geographic region in which the two species interbreed. Such hybrid zones offer a window on the speciation process, because the evolutionary dynamics involved in the intermingling of divergent genomes can be observed directly. Hybrid zones also offer the opportunity for adaptive genes or traits to move from one species to the other. Here, we performed the first genetic characterization of a hybrid zone between Red-billed and Black-billed Streamertail (Trochilus) hummingbirds in Jamaica. We sequenced three nuclear genes in a series of 100 hummingbirds collected along a transect spanning the transition from red-billed to black-billed birds. We found that bill color changes from red to black over only 15 kilometers (~9 miles), but over this same region nuclear gene frequencies did not change significantly. These results suggest that the forces maintaining the narrow transition in bill color (and the genes controlling bill color) are not acting on other regions of the genome. Future work will focus on increasing both the geographic sampling and the number of genes to help clarify what forces are maintaining the differences in bill color.
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