Systematics and Evolution of Body Size in Feather Lice (Phthiraptera: Columbicola)

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This project will explore co-speciation in a host-parasite system consisting of birds and their host-specific feather lice. Co-speciation takes place when parasite speciation (formation of new species) occurs in concert with host speciation. Repeated bouts of co-speciation result in host and parasite evolutionary trees that are mirror images of one another. The comparison of co-speciated evolutionary trees allows one to identify host-switching events, in which parasites "jump" from one ancestral host group to a new one. The bird-louse system provides a model in which it is possible to: 1) identify host-switching events by comparing evolutionary trees that have been reconstructed on the basis of DNA sequence data; and 2) determine under what conditions host switches are likely to occur. Specifically, are parasites more likely to "jump" between closely related species of hosts, or between species of hosts that are similar in body size or some other attribute? Host switching is an important evolutionary phenomenon with broad relevance to human health. For example, the HIV virus appears to have evolved as a result of a host switch from non-human primates to humans. Similarly, human malaria may have evolved from avian malaria. Birds and lice are a model system in which it is possible to uncover cases of host-switching (see above) in conjuntion with experimental simulations of switching that involve moving host-specific parasites among different species of hosts. Such experiments cannot be done with humans and must therefore be studied using animal model systems. This project has an important training component. A Ph.D. student will participate in all aspects of the work and several undergraduate research assistants will also receive training .