9411536 Jansen The use of DNA data in studying the phylogenetic or genealogical relationships among organisms has increased dramatically over the last few years. For most plant groups, the focus, for several methodological reasons, has been upon organellar DNA from the leaf chloroplast. Consequently, a major question is posed concerning whether mutational differences in chloroplast DNA are strongly correlated with mutational differences between plant species in their nuclear DNA, which is usually more difficult to analyze. Graduate student Dennis Loockerman, under the supervision of faculty adviser Robert Jansen at the University of Texas, is addressing this question in his study of a large group of sunflower relatives, the Tageteae. He will be analyzing large amounts of data from both chloroplast and nuclear DNA sets, comparing patterns of mutational differences among species, and reconstructing phylogenetic trees for this group of flowering plants. Results from the molecular studies will be integrated with traditional morphological characters, to improve classification of these plants and designate reliable identification features. Analysis of DNA data from both organellar and nuclear sources in a large group of sunflower relatives, the Tageteae, and integration with morphological characters, will improve taxonomic and phylogenetic understanding of these plants.
