CONICET | Buscador de Institutos y Recursos Humanos

The Octodontidae family is a characteristic group of rodents inhabiting South American aridlands and scrublands. The octodontids date back to late Miocene (7.79 Mya) with a major diversification during the Plio-Pleistocene. This is an ecomorphologically diverse group, composed of 13 species, from aboveground generalists to subterranean specialists, 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; distributional ranges were estimated from Nature Server Database and recent literature. Geographical regions were based on WWF Terrestrial Ecoregions. We used DIVA program to identify putative ancestral areas for each node. This, together with the divergence time estimated for this group, served to compare with known events of plate tectonic movements, Andean uplift, and major climate changes from Plio-Pleistocene to Holocene. Parsimony ancestral reconstruction for ecological character was performed using Mesquite program. Our results show that the ancestral area (i.e. ecoregions) for the Octodontidae group includes the Northern Monte, Mediterranean shrubland, central Puna and the Andean steppe. Two vicariant events occurred during its evolution. One corresponds to the Andean uplift which separated the Argentinean and Chilean octodontids. The second was associated with important volcanic activity in the Andean Puna, which separated O. gliroides from Chilean group. Divergence of Chilean octodontids was characterized by more recent dispersion and extinction. Terrestrial habits are suggested as the ancestral mode of life whereas fossoriality and semifossorial habits could be associated to new habitat types which emerged after the Andean uplift. We highlight the role of the Andes and associated environmental changes in the biogeography and ecology of this lineage ( Partially supported by grants from CONICET (PIP 5944) and AGENCIA (PICT 11768).