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Systematics Section / ASPT

Tremetsberger, Karin [1], Weiss-Schneeweiss, Hanna [1], Stuessy, Tod F. [1], Samuel, Rosabelle [1], Kadlec, Gertrud [1], Ortiz, Maria Ángeles [6], Talavera, Salvador [6], Urtubey, Estrella [2], Baeza, Carlos M. [3], Beck, Stephan G. [4], Valdebenito, Hugo [5].

NW African origin of South American Hypochaeris (Asteraceae, Cichorieae) and their subsequent rapid radiation elucidated by DNA sequencing and fingerprinting (AFLP).

Hypochaeris has a disjunct distribution, with some 15 species in the Mediterranean region, Macaronesia, Europe, and Asia, and more than 40 species in South America. Based o­n internal transcribed spacer (ITS) sequences and fluorescence in situ hybridization (FISH) with 5S and 18S-25S rDNA of the previously overlooked H. angustifolia from Moyen Atlas, Morocco, we show that it is sister to the entire South American group. The close relationship of H. angustifolia further supports the hypothesis of long-distance dispersal across the Atlantic Ocean for the origin of the South American taxa rather than the less parsimonious hypothesis of vicariance from Asia or northern Europe, through North America, followed by subsequent extinction o­n this latter continent. Based o­n assumption of a molecular clock, the trans-Atlantic dispersal from Morocco to South America can be estimated to have taken place between 3.00 to 4.75 mya (divergence of H. angustifolia and the South American group) and 0.75 to 2.50 mya (initial divergence within the South American group). Amplified fragment length polymorphism (AFLP) has been used to resolve relationships among South American species. These data, plus other factors such as geographical distribution, ecology, phenology, reproductive system, and geological history of regions, are used to formulate hypotheses about factors leading to rapid speciation in this group.

1 - University of Vienna, Institute for Botany, Dept. of Higher Plant Systematics and Evolution, Rennweg 14, Vienna, A-1030, Austria
2 - Museo de La Plata, División Plantas Vasculares, Paseo del Bosque, La Plata, 1900, Argentina
3 - Universidad de Concepción, Departamento de Botánica, Casilla 160-C, Concepción, , Chile
4 - Herbario Nacional de Bolivia, Casilla 10077, La Paz, , Bolivia
5 - Universidad San Francisco de Quito, Casilla 17-12-841, Quito, , Ecuador
6 - Facultad de Biología, Universidad de Sevilla, Dpto. de Biología Vegetal y Ecología (Botánica), Avenida Reina Mercedes 6, Sevilla, E-41012, Spain

long-distance dispersal
adaptive radiation

Presentation Type: Paper
Session: 43-8
Location: Cottonwood A (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 9:45 AM
Abstract ID:129

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