Systematics/Phytogeography / Taxonomie/ Section
Sears, Christopher , Whitton, Jeannette .
Taxonomic notes on the North American Crepis agamic complex: evidence from flow cytometry, morphology, and cpDNA sequence data.
The North American Crepis agamic complex is a Gordian knot of diploid, auto- and allopolyploid lineages comprising sexual and asexual individuals. Apomixis and polyploidy confound circumscription amongst the nine taxonomic species and the innumerable polyploid and apomictic lineages distributed throughout the western North American sagebrush steppe. As a result, the taxonomy of the complex is unsatisfying and evolutionary relationships remain nebulous. Ploidy levels range from diploid to octoploid. Ploidy and morphological analysis is a critical step in identifying taxonomic units in the complex. We are using flow cytometry to characterize ploidy variation within and among populations and species. When information on ploidy is compared with multivariate analysis of morphological variation, we find that some taxa that have been difficult to distinguish differ in ploidy. For example, C. atrabarba shares chloroplast haplotypes with C. barbigera and has overlapping suites of morphological characters. However, flow cytometry reveals that these taxa occupy mutually exclusive ploidy levels. Evidence gleaned from flow cytometry, morphology, and cpDNA sequence data are synthesized and the implications for taxonomic species boundaries are discussed.
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1 - University of British Columbia, Botany Department, 3529-6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
Presentation Type: Oral Paper:Papers for Sections
Location: Room 5/Woodward
Date: Tuesday, July 29th, 2008
Time: 1:15 PM