Systematics Section / ASPT
Derieg, Nathan , Bruederle, Leo P. .
A phylogeny of Carex section Ceratocystis emphasizing North American endemics.
Carex section Ceratocystis (Cyperaceae) comprises a distinct evolutionary lineage of eight species within this large genus. Previous research addressing evolutionary relationships in this section has revealed a trend of increasing chromosome number and decreasing longevity from a basal C. durieui to several more highly derived subspecific taxa within C. viridula. Allozyme data reliably discriminate among the North American endemics (C. lutea, C. cryptolepis, and a previously undescribed species), with phylogenetic analyses of these data providing some support for a monophyletic group. To further resolve the phylogenetic relationships among the North American endemic species and test the hypothesis of monophyly, we sequenced portions of nuclear ribosomal DNA including the continuous ITS 1 - 5.8S - ITS 2 region and the reportedly independently evolving ETS 1f. Carex lutea, a narrow endemic restricted to the Cape Fear watershed of North Carolina, and a previously unrecognized species from Ohio, Indiana, and Michigan are strongly supported as sister species. Although C. cryptolepis resolves as monophyletic with good support, it is not allied with the other North American endemics; rather, C. cryptolepis is nested within a poorly delimited group consisting of multiple accessions of C. flava and C. viridula. Incongruence of several phylogenetic hypotheses might be resolved by sequencing low copy nuclear genes (e.g., portions of the genes coding isocitrate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase), as well as variable chloroplast regions.
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1 - University of Colorado at Denver and Health Sciences Center, Biology, Campus Box 171, P.O. Box 173364, Denver, Colorado, 80217, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Stevens 3/Hilton
Date: Monday, July 9th, 2007
Time: 4:00 PM