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

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

Bariloche

Congreso; 6 Southern Connection Congress (Bariloche, Argentina); 2010

Species are impacted by climate change at different time scales. Studies in northern continents have documented dramatic shifts in distributions of species subsequent to the Last Glacial Maximum, particularly at high latitudes. However, little is known about the history of southern continents, especially at high latitudes. South America is the only continental, other than Antarctica, that extends significantly into latitudes higher than 40 °S. Genetic studies of a few Patagonian species have provided seemingly conflicting results, indicating either postglacial colonization from restricted glacial refugia or persistency through glacial cycles and in situ differentiation. Using mitochondrial DNA sequences of 14 species of sigmodontine rodents, a major faunal ensemble of Patagonia and Tierra del Fuego, we show that at least 9 of these species bear genetic footprints of demographic expansion from single restricted sources, although timing of demographic expansion precedes the Last Glacial Maximum in most, whereas four are fragmented phylogeographically. Our results indicate that a) demographic instability in response to historical climate change has been widespread in the Patagonian-Fueguian region, and is generally more pronounced at high latitudes in both southern and northern continents; b) colonization from lower latitudes is an important component of current Patagonian-Fueguian diversity; but c) in situdifferentiation has also contributed to species diversity.