Emshwiller, Eve , Gardner, Andrew , Oberlander, Kenneth C. , Vaio, Magdalena , Heibl, Christoph , Dreyer, Leanne .
Phylogeny and biogeography of Oxalis: preliminary results based on plastid loci.
The genus Oxalis comprises between 500 and 800 species, with the greatest number of species and diversity of forms found in South America and a large radiation of over 200 species in southern Africa. The genus includes species with a wide diversity of habits, including shrubs, creeping weeds, scandent vines, and succulent subshrubs. Many species are geophytic, with various storage structures such as tubers, tuberous roots, succulent stems (caudices), and two kinds of bulbs: tunicate bulbs in the southern African species and imbricate bulbs in those of the Americas. Alicia Lourteig’s classification is the most recent and thorough taxonomy of the genus on a global scale except for the southern African species. Recent studies of bulb evolution in Oxalis have addressed the question of whether bulbs had a single or multiple origin in the genus, but the results are as yet equivocal. As a team of international collaborators, we are working toward a broad exemplar-based molecular phylogeny of Oxalis, using DNA sequence data from several plastid and nuclear loci. Building this phylogeny will allow us to (1) determine the area of earliest diversification of the genus, (2) identify what parts of the subgeneric classification proposed by Alicia Lourteig are, or are not, congruent with the phylogenetic results, (3) determine whether the tunicate bulbs of southern Africa have a separate or a common origin with the imbricate bulbs of the Americas, (4) examine the relationship of bulb-bearing Oxalis taxa with those with other geophytic structures, including succulent caudiciform stems and rhizomatous stems bearing fleshy scales, to determine the sequence of evolution of these structures, (5) compare these results with morphological and developmental studies, especially of bulb characters. This presentation will focus on preliminary results of molecular analyses using sequences of several plastid loci, including trnS-trnT, trnT-trnL, trnL-trnL-trnF, trnS-trnG, psbA-trnH, psbJ-petA.
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1 - University of Wisconsin-Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
2 - University of Wisconsin Madison, Department of Botany, Birge Hall, 430 Lincoln Drive, Madison, Wisconsin, 53706-1381, USA
3 - Stellenbosch University, Department of Botany and Zoology, Private Bag X1 , Matieland, 7602, South Africa
4 - Universidad de la República , Laboratorio de Genética, Departamento de Biología Vegetal, Facultad de Agronomía, Montevideo, Uruguay
5 - University of Munich, Organismal Biology, Menzingerstr. 67, Munich, 80638, Germany
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Maybird/Cliff Lodge - Level C
Date: Wednesday, July 29th, 2009
Time: 8:15 AM