title: Nuclear ribosomal DNA and karyotypes indicate a NW African origin of South American Hypochaeris (Asteraceae, Cichorieae).
abstract: Hypochaeris has a disjunct distribution, with more than 15 species in the Mediterranean region, the Canary Islands, Europe, and Asia, and more than 40 species in South America. Previous studies have suggested that the New World taxa have evolved from ancestors similar to the central European H. maculata. Based on internal transcribed spacer (ITS) sequences and fluorescence in situ hybridization (FISH) with 5S and 18S-25S rDNA of the previously overlooked Hypochaeris angustifolia from Moyen Atlas, Morocco, we show that it is sister to the entire South American group. A biogeographic analysis supports the hypothesis of long-distance dispersal from NW Africa across the Atlantic Ocean for the origin of the South American taxa rather than migration from North America, through the Panamian land bridge, followed by subsequent extinction in North America. With the assumption of a molecular clock, the trans-Atlantic dispersal from NW Africa to South America is roughly estimated to have taken place during Pliocene or Pleistocene.
authors.affiliation: Department of Higher Plant Systematics and Evolution, Institute of Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria. k.tremetsberger@gmx.net
authors.forename: Karin
authors.initials: K
authors.lastname: Tremetsberger
authors.forename: Hanna
authors.initials: H
authors.lastname: Weiss-Schneeweiss
authors.forename: Tod
authors.initials: T
authors.lastname: Stuessy
authors.forename: Rosabelle
authors.initials: R
authors.lastname: Samuel
authors.forename: Gertrud
authors.initials: G
authors.lastname: Kadlec
authors.forename: Maria Angeles
authors.initials: MA
authors.lastname: Ortiz
authors.forename: Salvador
authors.initials: S
authors.lastname: Talavera
mesh_terms: D019659:Asteraceae / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D010802:Phylogeny
chemical_list: D004275:DNA, Ribosomal