Collaborative Research: Systematic Analysis of Evolutionary Radiation of Eupatorieae (Asteraceae)

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This collaborative research by Dr. Jose Panero from the University of Texas with colleague Dr. Edward Schilling at the University of Tennessee will analyze the systematic relationships and phylogenetic history of the Asteraceae (sunflower) tribe Eupatorieae. The tribe includes horticultural species such as sweetleaf and blazingstar, as well as noxious weeds such as Siam weed and Crofton weed. It is of particular interest for systematic studies because it has a large number of species (over 2400) and a widespread, primarily New World distribution, yet appears to be of relatively recent origin. A primary source of new information will be DNA sequence data from the chloroplast genome, and more than 10,000 base pairs of sequence data will be obtained from each of 180 samples representing 140 genera. Nuclear DNA sequences of the ribosomal regions totaling about 1,100 base pairs per sample will also be obtained. Assessments of these extensive data sets will rely on computer-based methods, including parsimony analysis, to produce a phylogeny ("family tree") that shows the relationships among members of the tribe. Comparison of the tree with data from other sources will be done to help understand the timing and sequence of morphological or chromosomal changes that have led to the species-level diversity of the tribe. The phylogenetic tree will also provide the basis to resolve contentious issues regarding the generic and subtribal classification of Eupatorieae. The result will be a more stable and predictive classification, and monophyletic groups will be identified that can be a target for future taxonomic studies to clarify the overall biodiversity of the tribe. This research will have broad and lasting impacts through its additions to the body of publicly available baseline information about Eupatorieae, training and education of students, and applications to resources about the family Asteraceae. The extensive fieldwork, much of it in tropical and subtropical areas that are actively threatened by human encroachment, to collect plant material will be documented by deposition of voucher specimens in scientific collections. Results of DNA sequence studies will be deposited at GenBank, a public database that is freely accessible by other researchers. Participation of graduate students in the research will provide training in basic systematics of a family that is large and widespread as well as in the laboratory and analytical procedures of molecular phylogenetics. The project will also provide opportunities for undergraduates to participate in research, and will coordinate with initiatives such as the McNair Program to target students from groups historically underrepresented in science research. New scientific findings from the research, including adjustments to the classification of Eupatorieae, will be documented by publication in peer-reviewed journals. Broader dissemination of the information will be accomplished by expansion of web-based resources to make information about systematics and phylogenetic relationships of Asteraceae widely available, using formats including images and graphics that make it accessible and understandable to the general public.