The Genetic Consequences of Long Generation Times

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Shaffer 9727161 This research program uses the analysis of DNA sequence variation to quantify levels of population differentiation in freshwater and terrestrial turtles from three continental regions: the central United States, the western and northern Amazon basin, and eastern Australia. In each of these regions, there have been severe climate changes during the past 15,000 years, and these changes have had impacts on the past and current distribution of all plants and animals, including turtles. For example, about 17,000 years ago most of North Dakota and Minnesota were under glacial ice, whereas today they are fully inhabited by species that have migrated north from warmer areas. DNA sequence data from at least two genes will be used to quantify the extent of these post-glacial migration patterns, focussing on turtles because they have very long generation times, and should show the maximal impacts of these past events in their current populations. More generally, these data will provide information on how one can use molecular genetic data from long-lived species to understand levels of migration, population fluctuations, and population stability. Such data are frequently utilized in disciplines ranging from conservation and managment to basic ecology and evolution, and they hinge on the assumption that past climatic fluctuations have has a negligable impact on current populations. These data will inform us on whether such assumptions are valid, or are in need of revision.