Pleistocene refugia and polytopic replacement of diploids by tetraploids in the Patagonian and Subantarctic plant Hypochaeris incana (Asteraceae, Cichorieae)

Authors

  • KARIN TREMETSBERGER,

    1. Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Apdo. 1095, 41080 Sevilla, Spain
    2. Department of Systematic and Evolutionary Botany, Faculty Center Biodiversity, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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  • ESTRELLA URTUBEY,

    1. Instituto de Botánica Darwinion, Labardén 200, B1642HYD San Isidro, Casilla de Correo 22, Buenos Aires, Argentina
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  • ANASS TERRAB,

    1. Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Apdo. 1095, 41080 Sevilla, Spain
    2. Department of Systematic and Evolutionary Botany, Faculty Center Biodiversity, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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  • CARLOS M. BAEZA,

    1. Departamento de Botánica, Universidad de Concepción, Casilla 160-C, Concepción, Chile
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  • MARÍA ÁNGELES ORTIZ,

    1. Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Apdo. 1095, 41080 Sevilla, Spain
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  • MARÍA TALAVERA,

    1. Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Apdo. 1095, 41080 Sevilla, Spain
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  • CHRISTIANE KÖNIG,

    1. Department of Systematic and Evolutionary Botany, Faculty Center Biodiversity, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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  • EVA M. TEMSCH,

    1. Department of Systematic and Evolutionary Botany, Faculty Center Biodiversity, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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  • GUDRUN KOHL,

    1. Department of Systematic and Evolutionary Botany, Faculty Center Biodiversity, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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  • SALVADOR TALAVERA,

    1. Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Apdo. 1095, 41080 Sevilla, Spain
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  • TOD F. STUESSY

    1. Department of Systematic and Evolutionary Botany, Faculty Center Biodiversity, University of Vienna, Rennweg 14, 1030 Vienna, Austria
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  • The research groups around T.F.S. (University of Vienna, Austria) and S.T. (University of Seville, Spain) collaborate with E.U. (Instituto de Botánica Darwinion, Argentina) and C.M.B. (University of Concepción, Chile) in research on evolutionary aspects of the genus Hypochaeris, in the Old World (mainly Mediterranean region) as well as in the New World (South America), addressing questions of genetic diversity and reproductive biology.

Karin Tremetsberger, Fax: +43 1 4277 9541; E-mail: k.tremetsberger@gmx.net

Abstract

We report the phylogeographic pattern of the Patagonian and Subantarctic plant Hypochaeris incana endemic to southeastern South America. We applied amplified fragment length polymorphism (AFLP) and chloroplast DNA (cpDNA) analysis to 28 and 32 populations, respectively, throughout its distributional range and assessed ploidy levels using flow cytometry. While cpDNA data suggest repeated or simultaneous parallel colonization of Patagonia and Tierra del Fuego by several haplotypes and/or hybridization, AFLPs reveal three clusters corresponding to geographic regions. The central and northern Patagonian clusters (∼38–51° S), which are closer to the outgroup, contain mainly tetraploid, isolated and highly differentiated populations with low genetic diversity. To the contrary, the southern Patagonian and Fuegian cluster (∼51–55° S) contains mainly diploid populations with high genetic diversity and connected by high levels of gene flow. The data suggest that H. incana originated at the diploid level in central or northern Patagonia, from where it migrated south. All three areas, northern, central and southern, have similar levels of rare and private AFLP bands, suggesting that all three served as refugia for H. incana during glacial times. In southern Patagonia and Tierra del Fuego, the species seems to have expanded its populational system in postglacial times, when the climate became warmer and more humid. In central and northern Patagonia, the populations seem to have become restricted to favourable sites with increasing temperature and decreasing moisture and there was a parallel replacement of diploids by tetraploids in local populations.

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