Mammalian biogeography of Patagonia and Tierra del Fuego

Abstract

The Patagonian-Fuegian region, located in southern South America roughly south of 40°S, comprises areas of Argentinean monte, Patagonian steppe and grasslands, and Valdivian temperate and Magellanic subpolar forests. Although the area was aff ected by the glacial cycles of the Neogene, glacial sheets were typically much more limited in South America than in northern continents. In this context, we review distributional, phylogenetic, phylogeographic, and population genetic information on the composition and historical biogeography of mammals in the region. Although many species are likely relatively recent colonizers of the region, distributional and phylogenetic data provide several examples of endemic species and others that likely resulted from local diversifi cation. Phylogeographic analyses provide additional indications of diff erentiation within the region. Phylogeographic breaks divide species distributions by latitude rather than between major habitats. Population genetic analyses reveal several cases of demographic expansion, all of which can be assigned to the late Pleistocene (i.e., the last 500,000 years). However, very few of these can be attributed to events postdating the Last Glacial Maximum (∼21,000 BP). Overall, the current mammalian fauna of Patagonia and Tierra del Fuego is the result of a complex mix of local fragmentation, diff erentiation, and colonization from lower latitudes.