Patterns of genetic diversity and the history of sigmodontine rodents in Patagonia.

LESSA, E.; D'ELÍA, G.; PARDIÑAS, U.F.J.

Congreso; 10 International Mammalogical Congress (Mendoza, Argentina); 2009

IFM-SAREM

Genetic studies of continental species of mammals at high latitudes have generally revealed complex histories, including phases of geographical isolation in glacial refugia and subsequent colonization during interglacial phases. Our understanding of such process in the Patagonian-Fueguian region is based on a limited number of studies. We present results of a survey of 14 species of sigmodontine rodents, which represent an important component of the mammalian fauna of the region, on the basis of DNA sequences of the mitochondrial cytochrome b gene and of two nuclear introns. At least 10 of these species show evidence of demographic expansion, presumably from source areas more restricted tan their current distributions. However, in several cases the estimated timing of such events of demographic expansion is older than expected for populations that have expanded subsequent to the last glacial maximum. In addition, several species show marked phylogeographic structure that suggests differentiation in more than one geographical area. More generally, although several species may be relatively recent colonizers of the Patagonian region, others show evidence of a deeper history within the region that has included opportunities for in situ differentiation.