Systematics/Phytogeography / Taxonomie/ Section
Youngstrom, Sarah , Kellogg, Elizabeth .
A morphometric study of Panicum virgatum and P. amarum in the Southeastern United States.
Taxonomy of Panicum virgatum and its sister taxa Panicum amarum is problematic. Classifications regarding species delimitations have conflicted due to morphological similarities especially in regions where they co-occur. In addition, previous literature has suggested that hybridization may contribute to the variation in forms. A different perspective is necessary to begin to revise the taxonomy. Previous classifications were based on data collected across a large area of distribution. Consequently, this broad sampling may mask the true diversification patterns since P. virgatum and P. amarum have been reported to exhibit morphological clines. Although morphological overlap has been frequently documented, multivariate analysis has not been conducted on this group. I am using multivariate analyses on a localized scale in attempts to begin to revise the taxonomy. My study focuses on the southeastern United States, a region of species overlap. I am using 26 characters for my analysis including quantitative vegetative, inflorescence, and floral measurements on 100 specimens. Panicum urvilleanum, whose North American distribution is solely on the southwestern coast, serves as an outgroup for the study. Principle component analysis (PCA) show a continuum, and a strong correlation in floral characters, but no distinct groupings. These results support the previous literature that indeed this is a complex and perhaps hybridizing taxa, but on a local scale. Additional information regarding karyotype and geography will be added to analysis.
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1 - University of Missouri-St. Louis, Biology, One University Boulevard, R223 Research Building, St. Louis, MO, 63121-449, USA
2 - University of Missouri St Louis, Department of Biology, 8001 Natural Bridge Road, St Louis, Missouri, 63121-4499, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 11:30 AM