Systematics Section / ASPT
Krosnick, Shawn , Freudenstein, John , Potter, Daniel .
Phylogenetic relationships, rates of speciation, and biogeographical patterns in the Old World Passiflora (subgenus Decaloba: supersection Disemma).
Passiflora is comprised of more than 520 species distributed primarily throughout Mexico, Central and South America, and the Caribbean. However, an additional 21 species of Passiflora are endemic to Australia, Papua New Guinea, China, India, and Southeast Asia. The Old World species are currently recognized within subgenus Decaloba, supersection Disemma. Previous analyses indicated that Disemma is monophyletic, but the details of the relationships both within the supersection and of Disemma to the rest of the genus were unknown. In order to address these questions, four molecular loci (trnL-F, ITS, ncpGS and cytGS) and 39 morphological characters were used to reconstruct the evolutionary history of Disemma. Both parsimony and Bayesian analyses were utilized for the molecular dataset. Results strongly support the monophyly of supersection Disemma and resolve two monophyletic lineages and one monotypic lineage within the clade: section Hollrungiella (1 species), Disemma (3 species), and Octandranthus (17 species). The phylogenetic position of supersection Disemma relative to the other supersections in Passiflora was ambiguous. Supersection Disemma is not supported by any clear morphological synapomorphies, and there are few uncontroverted synapomorphies at the sectional level or below. The level of morphological variation observed in both floral and vegetative characters raises questions about the timing and rate of diversification in supersection Disemma. It is possible that Disemma represents a recent and rapid radiation, or alternatively, the clade might be much older and taxa with transitional morphologies may be extinct. Penalized likelihood was used to estimate absolute divergence times within Disemma, and relative speciation rates were also inferred. These data were then used to place Disemma within the context of its environment at the time, and to examine the mode and direction of its diversification throughout the Old World.
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1 - University of California, Davis, Plant Sciences, One Shields Avenue, Davis, CA, 95616, USA
2 - Ohio State University, Department of Evolution, Ecology and Organismal Biology, Museum of Biological Diversity, 1315 Kinnear Rd., Columbus, Ohio, 43212, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Stevens 3/Hilton
Date: Wednesday, July 11th, 2007
Time: 10:30 AM