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

K. TREMETSBERGER; E. URTUBEY; A. TERRAB; C. M. BAEZA; M. A. ORTIZ; M. TALAVERA; C. KONIG; S. TALAVERA; T. F. STUESSY

MOLECULAR ECOLOGY

Blackwell Publishing Ltd.

Lugar: Loughborough; Año: 2009 vol. 18 p. 3668 - 3682

0962-1083

AbstractWe report the phylogeographic pattern of the Patagonian and Subantarctic plantHypochaeris incana endemic to southeastern South America. We applied amplifiedfragment length polymorphism (AFLP) and chloroplast DNA (cpDNA) analysis to 28 and32 populations, respectively, throughout its distributional range and assessed ploidylevels using flow cytometry. While cpDNA data suggest repeated or simultaneousparallel colonization of Patagonia and Tierra del Fuego by several haplotypes and ⁄ orhybridization, AFLPs reveal three clusters corresponding to geographic regions. Thecentral and northern Patagonian clusters (38–51 S), which are closer to the outgroup,contain mainly tetraploid, isolated and highly differentiated populations with lowgenetic diversity. To the contrary, the southern Patagonian and Fuegian cluster (51–55 S) contains mainly diploid populations with high genetic diversity and connected byhigh levels of gene flow. The data suggest that H. incana originated at the diploid level incentral 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 thatall three served as refugia for H. incana during glacial times. In southern Patagonia andTierra del Fuego, the species seems to have expanded its populational system inpostglacial times, when the climate became warmer and more humid. In central andnorthern Patagonia, the populations seem to have become restricted to favourable siteswith increasing temperature and decreasing moisture and there was a parallel replacementof diploids by tetraploids in local populations.Keywords: amplified fragment length polymorphism, chloroplast intergenic spacer regions,flow cytometry, phylogeography, South America, Tierra del FuegoReceived 9 September 2008; revision received 15 May 2009; accepted 4 June 2009