DISSERTATION RESEARCH: Trajectories of Genetic Change in Populations With Different Founding Sizes: Time Transects of Daphnia Populations in Two Upstate New York Lakes

Cornell University, Ithaca NY

Investigators

Abstract

Long-term effects of population reductions on genetic diversity are well understood, but few studies have examined short-term changes in genetic diversity in populations immediately after they have been founded. The goal of this project is to compare changes in genetic diversity in three species of the grazing zooplankter Daphnia that recolonized a lake from a small number of founding individuals with a fourth population that was founded by a large number of individuals. Long-lived dormant Daphnia eggs in sediments record annual changes in populations that can be reconstructed from sediment cores. Genetic diversity of each of the four "populations" at several time points following recolonization will be measured to assess changes as the populations recovered in size. Daphnia species are a key component of aquatic ecosystems, serving as a control on algae and a food source for fish. The ability of a population to respond to environmental changes depends on the level of genetic diversity present. This study will thus provide important insights into how Daphnia respond to environmental change and influence community and ecosystem processes. It will also provide empirical tests of theoretical models and contribute to our knowledge about how genetic diversity is maintained in natural populations, which in turn will foster more appropriate management or conservation plans.