Bridging Micro and Macroevolutionary Patterns: Population Genetics of Coevolutionary History

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Jason Weckstein and John Bates of the Field Museum and Alex Aleixo of the Museu Paraense Emilio Goeldi will use DNA sequencing technology to reconstruct the history of associations between two codistributed toucan host groups and two of their parasitic chewing louse genera. Their main objective is to determine how different parasite groups, which differ in features of their biology and ecology, respond to identical geographical and habitat perturbations (diversification and speciation of the hosts). Studies of hosts and permanent ectoparasites provide a unique opportunity to reconstruct the history and the environmental context in which the processes of diversification and speciation occur. Permanent ectoparasites are hypothesized to share a common evolutionary history with their hosts, therefore, one can reconstruct this history of interactions between hosts and parasites by superimposing the parasite's evolutionary history onto the host's evolutionary history. The replicate parasite lineages included in this study live their entire life cycles on the same avian hosts, yet are members of different louse suborders that differ in a variety of biological and ecological features. By comparing these replicate parasite groups, this study will assess how unique features of each parasite's biology correlate with diversification in the hosts. Insights gained in this simple system will shed light on patterns of speciation and diversification in the more complex systems of free-living organisms. This project also has a number of important societal benefits. First, this work will document basic patterns of biological diversity in Amazonia, one the earth's richest ecosystems. It also will involve international collaboration between US and Brazilian researchers from the Field Museum of Natural History and the Museu Paraense Emilio Goeldi. Researchers and students will travel between these two institutions to teach, learn, work, and collaborate with each other to further our understanding of speciation and diversification in the tropics. This international collaboration will provide an unprecedented opportunity to study patterns of diversification and speciation in the Amazon. Second, studies of lice and their vertebrate hosts have played a prominent role in understanding the historical associations of hosts and their parasites. Theories and analytical methods developed using these model organisms have been applied to other systems such as vertebrates and their viruses, which are critical to human health issues. This project will further the biological understanding of these kinds of systems and will help us to understand the ecological characteristics that provide opportunities for disease causing parasites to jump between hosts.