Crawford, Daniel , Kimball, Rebecca , Tadesse, Mesfin , Mort, Mark .
Radiation of Coreopsis section Pseudoagarista (Asteraceae)in the Andes.
The largest lineage within the genus Coreopsis (Asteraceae)occurs in South America where some 36species in section Pseudoagarista occur at higher elevations in the Andes. About 10 other species assigned to Pseudoagarista occur in Mexico, making the section disjunct between North and South America. Analyses of DNA sequences indicate that the species within each of the geographic areas arose from a common ancestor (each is monophyletic), but whether all members of section Pseudoagarista are monophyletic has not been resolved because different DNA sequences give conflicting results. Most species in South America are very similar in floral features and are distinguished only by leaf form; examination of herbarium material suggests that some described species are minor leaf variants, but additional study of natural populations is needed. Some species are of very restricted geographic distribution. Polyploidy has been important in the diversification in the Andes, with three different ploidal levels known. DNA sequences resolve some relationships among South American species, but the level of divergence is low,and suggests a recent origin for some of the recognized species. By contrast, levels of sequence divergence are higher among the Mexican species, and even higher divergence is found between Mexican and South American taxa. Some species in South America are cross-compatible (can hybridize) whereas others are not. Diversification in South American Coreopsis has been promoted by several mechanisms and these will be compared and contrasted with other plant radiations in the Andes.
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1 - University Of Kansas, Department Of Ecology And Evolutionary Biology, 1200 Sunnyside Avenue, Haworth Hall, Lawrence, KS, 66045-7534, USA
2 - University of Floria
3 - The Ohio State University
4 - University Of Kansas, Ecology and Evolutionary Biology & Biodiversity Institute, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Franklin A/Hyatt
Date: Monday, July 9th, 2012
Time: 11:15 AM