GEOGRAPHICAL DISTRIBUTION AND DIVERSIFICATION IN SOUTH AMERICAN OCTODONTID RODENTS (RODENTIA, CAVIOMORPHA)

A. OJEDA; A. NOVILLO; R. OJEDA; S. ROIG

Mendoza, Argentina

Congreso; Xth International Mammalogical Congress; 2009

International Federation of Mammalogists

The Octodontidae is a characteristic family of rodents inhabiting South American aridlands and scrublands. The octodontids date back to late Miocene with a major diversification during the Plio-Pleistocene. Is an ecomorphologically diverse group, composed of 13 species, with their geographical ranges extending along both sides of the Central-Southern Andes. In this presentation we propose a biogeography hypothesis for their major clades and explore the evolutionary history of their ecological characters (e.g. modes of life). We used a phylogeny of 11 Octodontids. The distributional ranges were estimated from Nature Server Database and geographical regions were based on WWF Ecoregions. We used DIVA to identify putative ancestral areas for each node. This, together with the divergence time estimated for this group, served to compare with geologic and climatic events, such as Andean uplift, and major climate changes from Plio-Pleistocene to Holocene. Parsimony ancestral reconstruction for ecological character was performed using Mesquite. Our results show that the ancestral area (i.e. ecoregions) for the Octodontids includes: Northern Monte, Mediterranean shrubland, central Puna and Andean steppe. Two vicariant events, related with the Andean uplift occurred during its evolution. The first one split two clades, separating species of restricted lowland areas of Monte from Chilean and high mountains species of Argentina. The second event could be related with the formation of high altitude habitats generate for the paulatine Andean uplift, splitting Chilean species from species that inhabit the Bolivian and Argentinean Puna. Divergence of Chilean octodontids was characterized by more recent dispersion events. Terrestrial habits are suggested as the ancestral character whereas fossorial habits could be associated to “new” habitats which emerged after the Andean uplift. We highlight the role of the Andes associated and environmental changes in the biogeography and ecology of this lineage (Partially supported by CONICET (PIP 5944) and AGENCIA (PICT 1176).