0126631 Drs. Peter Fritsch and Frank Almeda at the California Academy of Sciences and their colleagues are studying the phylogenetic relationships of the tropical flowering plant genus Symplocos with DNA sequence data to test competing hypotheses on the evolution of organisms with "amphi-Pacific tropical" distributions. These are groups of plants that occur today primarily or exclusively in the tropical areas of the Americas and the lands bordering the western Pacific Rim. The means by which these land organisms have come to occupy areas that are today separated by thousands of miles of Ocean are not well understood. One hypothesis explaining this pattern proposes intercontinental dispersion across one or both of the land bridges connecting North America and Eurasia in the Early Tertiary around the high-latitude regions of Beringia and the North Atlantic. A competing hypothesis maintains that the primary avenue for the dispersion of these plants occurred pan-tropically in the Late Cretaceous/Early Tertiary, when the Atlantic Ocean was much narrower than today. The investigators will analyze DNA sequence data from Symplocos samples to estimate both the pattern of species relationships and intercontinental splitting times of major subgroups. These data will in turn be interpreted in the context of the extensive fossil record of Symplocos to arrive at a synthetic view of the biogeographical history of this group. The project will integrate laboratory work with field collection of samples from several countries, in Latin America and S.E. Asia. The broader scientific significance and societal ramifications of this project will benefit both environmental protection and science education. By facilitating inferences about the past movements of tropical vegetation, the knowledge derived from this project will contribute to the broader issues of the ecological effects of climate changes that are occurring at present. Further, it will help develop and refine conservation strategies of tropical countries, as many Symplocos species are rare and endangered. The project will contribute to the support and training of the next generation of organismal biologists by including undergraduate, Masters, and Ph.D. students involved in original research projects. Because the proposed research will be conducted at a major metropolitan natural history museum, ample opportunities exist to present the results of this research and its implications to the general public. This will take the form of articles in popular periodicals, displays in the museum's public venues, adult education courses, and lectures for visitors.