Systematics Section / ASPT
Hardy, Christopher R. , Linder, H. Peter .
A phylogeny for the African Restionaceae and new perspectives on morphology’s role in generating complete species-phylogenies for large clades.
There are a number of difficulties with obtaining complete species-level phylogenies. These difficulties include (1) the accurate identification and sampling of species, (2) the collection of molecular data for each species, and (3) resolving relationships among closely related species. We addressed these in an investigation of phylogenetic relationships among all 292 members of the Restio-subclade of the African Restionaceae. With outgroup taxa the combined analysis included 317 taxa, placing it among the largest species-level phylogenetic studies to-date. Accurate species identification and collection in the field was facilitated by a morphology-based interactive key to all species. Despite intensive fieldwork, however, material for DNA extraction could not be obtained for 20 of the 292 Restio-subclade taxa. Furthermore, the 6831 aligned nucleotides and 1782 parsimony-informative sequence characters were insufficient to fully resolve relationships. The coding of indel characters provided a very minimal increase in resolution and a simulation indicated that at least 5000-7000 additional bases may have been needed to achieve supported resolution in the neighborhood of 95-100%. Upon integrating a large number of morphological characters from the interactive key to species developed originally for field identification, parsimony resolution increased 17% to nearly 100%, and overall support increased in both parsimony and Bayesian frameworks. Taxa for which DNA data were lacking could be placed in fully resolved positions. Experiments using the Parsimony Ratchet indicated that placement of these morphology-only taxa may have been accurate to genus 96% of the time, and accurate to sister species/group 30% of the time, to within three nodes of the sister group 60% of the time, and to within 10 nodes 90% percent of the time. Accurate placement of morphology-only taxa through Bayesian analysis may require extensive exploration of tree and parameter space and thus may be more difficult with large groups such as the African Restionaceae.
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1 - Millersville University, James C. Parks Herbarium, Biology Department, Millersville, PA, 17551, USA
2 - Universität Zürich, Institut für Systematische Botanik, Zollikerstrasse 107, Zürich, CH-8008, Schweiz
Cape Floristic Region
Presentation Type: Oral Paper:Papers for Sections
Location: Continental A/Hilton
Date: Tuesday, July 10th, 2007
Time: 8:00 AM