CONICET | Buscador de Institutos y Recursos Humanos

For Calceolaria polyrhiza we aimed to determine whether phylogeographic patterns corresponded to in situ Pleistocene survival or to glacial retreat and postglacial expansion and, to reveal putative glacial refugia and post-glacial colonization routes. Haplotypes (27) of the trnH-psbA- intergenic cpDNA spacer were obtained from 68 populations (590 indiv.) covering the entire range of this widely distributed Patagonian endemic herb occurring both in the temperate forests and arid steppe. Three phylogeographic breaks revealed four major lineages: two high Andean split first during the late Miocene, and two Patagonian, ca 4 Ma BP coincident with the steppe establishment. The Patagonian groups exhibited diversification, rapid population expansion and colonization of the Andes flanks to the end of the Pleistocene. Populations in formerly ice-covered locations are monomorphic for the four most abundant haplotypes, suggesting recent independent colonizations by zonal steppe lineages. Highest diversity spots were found along a N-S transect congruent with the GPG ice-sheet limits. Past climate fluctuations influenced on diversification, distribution and demography of this plant. A scenario of multiple periglacial Pleistocene refugia and subsequent multiple recolonization routes, from east Patagonia to the Andean flanks, is proposed. The phylogeographic structure also preserves imprints of older phenomena, suggesting multiple and complex processes may moulded biodiversity in Patagonia.