Systematics/Phytogeography / Taxonomie/ Section
Ford, Bruce A. , Naczi, Robert F. C. , Starr, Julian R. , Ghazvini, Habibollah .
Phylogeny of Carex subg. Vignea (Cyperaceae) based on amplified fragment length polymorphisms (AFLPs) and non-coding nrDNA sequence data.
Carex subg. Vignea is a distinctive taxon (c. 300 spp., 28 sections) usually characterized by sessile, bisexual spikes, distigmatic flowers, and the lack of cladoprophylls. In this study we examine evolutionary relationships in Carex subg. Vignea using AFLP data alone and in combination with nrDNA ITS and ETS 1f sequences. Parsimony and Bayesian analyses of the combined dataset (959 AFLP loci, 1415 nrDNA base pairs + indels, 90 vignean taxa) show subg. Vignea to be monophyletic with the atypical C. gibba (gynaecandrous spikes, tristigmatic flowers, cladoprophylls) as sister to the remainder of the subgenus. All gynaecandrous sections are monophyletic, with gynaecandry having arisen multiple times. Conspecific samples and morphological species complexes (e.g., C. gynocrates/dioica, C. stipata/laevivaginata, etc.) always form sister groupings. In contrast, androgynous sections are largely polyphyletic with most clades comprised of disparate assemblages of taxa that are difficult to correlate with morphology or geography. Bootstrap values/posterior probabilities support terminal and basal clades, though important topological differences between parsimony and Bayesian trees exist along the backbone. Nonetheless, Bayesian analyses are more consistent with species morphology, suggesting that the high levels of homoplasy observed within the combined dataset are best addressed by a model-based method. Bayesian and neighbor-joining analyses of the AFLP data alone result in trees that are topologically similar to the Bayesian analysis of the combined data. In groups such as subg. Vignea, which may be recently evolved, AFLPs provide a rich source of highly variable characters that give good support for terminal clades. However, high rates of homoplasy may limit their application in higher-level phylogenetic studies.
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1 - University of Manitoba, Department of Biological Sciences, Winnipeg, Manitoba, R3T 2N2, Canada
2 - Delaware State University, Claude E. Phillips Herbarium, Department Agriculture & Natural Resources, 1200 N Dupont Highway, Dover, Delaware, 19901-2277, USA
3 - University of Ottawa, Department of Biology, Ottawa, Ontario, K1N 6N5, Canada
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 9:30 AM