Systematics/Phytogeography / Taxonomie/ Section
Steele, Roxi , Gilbert, Larry , Jansen, Robert K. .
Systematics of the Neotropical Genus Psiguria (Cucurbitaceae).
Found only in the New World tropics, Psiguria is a small but important group of vines whose members have mutualistic relationships with their pollinators, Heliconius butterflies. Since the phylogeny of the butterflies has been proposed, a phylogenetic framework of Psiguria is the missing information needed to fully investigate the significance of potential coevolutionary relationships. Additionally, Psiguria has an interesting distribution in Central and South America with two species endemic to the geologically complex islands of the Caribbean, inspiring important questions about its biogeographic history. Furthermore, Psiguria has a confused taxonomic history due to several life history strategies: 1) great variation in leaf morphology between immature and adult plants, 2) monoecious but temporally separated male and female flowers, and 3) a lack of morphological variation between proposed species. Our preliminary results represent the first effort to reconstruct the evolutionary history of Psiguria and sort out discrepancies between the 17 validly published names and the eight names applied to 90% of herbarium specimens. A family-wide phylogeny of Cucurbitaceae supported the monophyly of the subtribe Guraniinae, but relationships at the generic level raised doubts about the monophyly of Psiguria. In this ongoing study, the monophyly of Psiguria is being tested using multiple data sets, greatly expanded taxon sampling, and several outgroups. Our phylogenetic estimation of relationships within Psiguria is based on a concatenated chloroplast marker containing eight noncoding regions totaling over 7,000 base pairs and on ITS, with preliminary investigations into two low-copy nuclear markers. Phylogenetic analyses were conducted with several different computer algorithms including Maximum Parsimony, Maximum Likelihood, and Bayesian analyses. Results from the various data sets support the monophyly of Psiguria with moderate to strong bootstrap support. Our study will eventually determine the extent of the morphological and molecular variation within Psiguria, and assist in elucidating relationships within the genus.
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Roxi Steele's webpage on Psiguria
1 - University of Texas Austin, Plant Biology Graduate Program, 1 University Station A6720, Austin, Texas, 78712, USA
2 - University of Texas at Austin, Section of Integrative Biology, 1 University Station, #A6700, Austin, TX, 78712, USA
3 - University of Texas at Austin, Section of Integrative Biology, 1 University Station, #A6700, Austin, TX, 78712, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, July 30th, 2008
Time: 3:45 PM