Systematics Section / ASPT
Mansion, Guilhem , Kissling, Jonathan .
The polyphyletic genus Sebaea (Gentianaceae): new insights in the biogeography of the primarily South-African tribe Exaceae.
SEBAEA Sol. (Gentianaceae) is a primarily South African species-rich genus (c. 100 species) whose taxonomy is still unclear and confusing. In this study, we used a combination of molecular, karyological, and morphological evidences to infer the evolutionary history of this group, and its phylogenetic position within the tribe Exaceae. Parsimony and Bayesian analyses, based on both cpDNA (trnL-F region) and nrDNA (ITS region) sequences, confirmed the monophyly of the tribe Exaceae, and revealed a polyphyletic genus Sebaea with two well-supported clades. The first clade - Sebaea sensu stricto - comprised primarily South African species. The second clade - the resurrected genus Exochaenium — was sister to a large (Exacum + Tachiadenus + Ornichia + Gentianothamnus) clade. The distinction between Sebaea and Exochaenium was further supported by morphological and karyological evidences. Finally, biogeographical reconstructions supported a South Africa + Cape Region origin (Sebaea) for the tribe, followed by dispersals to Central Africa (Exochaenium), Madagascar (Exacum, Tachiadenus, Ornichia, Gentianothamnus), and Asia (Exacum).
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1 - Universität Zürich, Institut für Systematische Botanik, Zollikerstrasse 107, Zürich, CH-8008, Schweiz
2 - University of Neuchatel, Evolutionary Botany, Emile Argand 11, Neuchatel, NEU, 2000, Switzerland
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM