Systematics Section / ASPT
Starr, Julian R. , Ford, Bruce A. .
Evolution in sedges (Cariceae, Cyperaceae): current knowledge and future directions.
In this study, we review the impact of DNA sequence analyses on our understanding of Cariceae phylogeny and classification, and we explore character evolution using an nrDNA ITS + ETS 1f analysis of 105 taxa from four different studies. Analyses included all recognized genera (Carex, Cymophyllus, Kobresia, Schoenoxiphium, Uncinia) and Carex subgenera (Carex, Psyllophora, Vignea, Vigneastra). As in previous analyses, four major Cariceae clades were recovered: (1) a “Core Carex Clade” (subg. Carex, Vigneastra, Psyllophora p.p); (2) a “Vignea Clade” (subg. Vignea, Psyllophora p.p.); (3) a “Schoenoxiphium Clade” (Schoenoxiphium, subg. Psyllophora p.p.), and (4) a “Core Unispicate Clade” (Uncinia, Kobresia, subg. Psyllophora p.p.). All Cariceae analyses to date provide strong support (86 – 100% BS) for the Core Carex and Vignea Clades, but only weak to moderate support (< 50% – 78% BS) for the Core Unispicate and Schoenoxiphium Clades. The relationships of these groups are unresolved. Studies suggest that Carex is either paraphyletic with respect to all Cariceae genera or to all genera except Schoenoxiphium. Kobresia is a grade, but Uncinia and possibly Schoenoxiphium are monophyletic. The monotypic Cymophyllus is indistinct from Carex subg. Psyllophora species. Character analyses indicate that inflorescence proliferation and reduction have occurred in all major clades, and that the Cariceae’s unisexual flowers have evolved from perfect flowers. The ancestor to Cariceae possessed a multispicate inflorescence with cladoprophylls and female spikelets with tristigmatic gynoecia and closed utricles. This morphology is most similar to extant Carex subg. Carex species. Since taxonomic sampling and statistical support for phylogenies has been poor, we advocate the temporary maintenance of the four traditional Carex subgenera with androgynous unispicate species placed within subg. Psyllophora and dioecious and gynaecandrous unispicate species distributed amongst subgenera Carex and Vignea. Recommendations for future Cariceae research will be discussed.
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J. Starr Homepage
B. Ford Homepage
1 - University of Ottawa, Department of Biology, Ottawa, Ontario, K1N 6N5, Canada
2 - University of Manitoba, Department of Botany, Winnipeg, Manitoba, R3T 2N2, Canada
Presentation Type: Oral Paper:Papers for Sections
Location: Stevens 3/Hilton
Date: Monday, July 9th, 2007
Time: 3:45 PM