DISSERTATION RESEARCH: Molecular Systematics of Carex (Cyperaceae)

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9623421 Olmstead Graduate student Alan Yen, with direction from adviser Richard Olmstead at the University of Washington, is studying the large sedge genus Carex, with an emphasis on collecting new molecular data from nuclear and chloroplast gene sequences. Large genera, by virtue of the sheer number of species, are intimidating subjects of taxonomic research, and Carex is one of the largest with over 2,000 described species worldwide. It is also considered an ecologically significant group of plants, especially in wetland habitats, and for such purposes as wildlife forage and shelter and storm water retention. To enhance reliability of species recognition in the genus, improve sectional classification, and infer a phylogeny for the group, research is being conducted to add new molecular evidence to existing morphological features used in Carex taxonomy. Field work in Malaysia and Taiwan has provided samples of critical exemplar taxa, and colleagues in other parts of the world are supplying valuable materials for study. Preliminary molecular data are promising; DNA nucleotide sequence data will provide direct measures of mutation differences between taxa, and allow inference of phylogenetic relationships among the species. The project adopts an exemplar approach to taxon sampling, with the hope that analysis of 75-100 species can provide a robust phylogenetic framework for the genus as a whole. For a large genus like Carex, with 2,000+ species and with a limited suite of morphological and anatomical characters available for taxonomic discrimination and phylogenetic resolution, new sources of evidence are needed. This project offers gene sequencing of nuclear and chloroplast DNA as a source of new data, from a wide sample of species collected throughout the world. Analysis of the new molecular data and integration with traditional morphological characters hold promise for providing a phylogenetic framework for the group, in turn useful for future intensive investigations in systemati cs and ecology of these plants.