Dissertation Research: Phylogeny and Character Evolution in Yucca L. Based upon Morphological and Molecular Analyses

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9410882 Simpson Graduate student Karen Clary, under the supervision of faculty adviser Beryl Simpson at the University of Texas, is studying the taxonomy and phylogeny of the desert genus Yucca, estimated to encompass ca. 35 species in Mexico and the U.S. Morphological, anatomical, and molecular (DNA) analyses are being conducted to provide comparative data for assessing genealogical affinities. The internal transcribed spacer region of the nuclear ribosomal DNA repeat will be sequenced to determine mutational differences in nucleotide composition among species. Results from nuclear DNA analyses will be compared to those based upon chloroplast DNA studies for the same species. Molecular and morphological characters will be combined to achieve a reliable classification of the plants. An understanding of patterns of diversity in molecular and morphological features in Yucca will provide answers about the origin of the genus and its evolution in relation to desert conditions, in general, and in particular should prove interesting when compared with phylogenetic data on yucca moths, the chief pollinators of these plants.