Dissertation Research: Phylogenetic Systematics and Biogeography of Hawaiian Dryopteris (Dryopteridaceae)

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Species boundaries, evolutionary relationships, and the historical biogeography of Hawaiian members of the fern genus Dryopteris (Dryopteridaceae) will be explored using both DNA sequence data and morphological data. Dryopteris is a cosmopolitan genus comprised of approximately 250 species. Nine to 16 endemic species and one non-endemic species of Dryopteris occur in the Hawaiian Islands. Species boundaries, as delimited by past morphological studies, are unclear. This research will use both molecules and morphology to address objectively the issue of species delimitations. Although confusion about numbers of species exist, it appears that the species diversity observed in Hawaii was a result of multiple, successful colonization events to the Hawaiian Islands. This study aims to determine the number of Dryopteris species present in Hawaii, the evolutionary relationships among those species, and biogeographical origins of Hawaiian Dryopteris. Although several phylogenetic and biogeographical studies have been performed for flowering plants in Hawaii, to date there are no published phylogenies for any pteridophyte group occurring in Hawaii. Pteridophytes make up about 1/5 of the native vascular plant species in Hawaii and this lack of phylogenetic information about pteridophytes represents a large gap in our understanding of the evolution of the Hawaiian flora. Additionally, the proposed research is of critical importance to the study of evolution on islands in general, and on the Hawaiian Islands in particular, because we will elucidate the phylogenetic and biogeographical history of a group of endemic species that probably represents multiple independent colonizations of the archipelago. Our results will help elucidate biogeographical processes that may contribute significantly to the biological diversity of islands.