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

OJEDA AGUSTINA; NOVILLO AGUSTINA; ROIG JUÑENT, SERGIO; OJEDA RICARDO

Mendoza

Congreso; 10 th Mamalogical International congres; 2009

IADIZA

The Octodontidae is a characteristic family of rodents inhabiting South American aridlands and scrublands. The octodontids dateback to late Miocene with a major diversification during the Plio-Pleistocene. Is an ecomorphologically diverse group, composed of13 species, with their geographical ranges extending along both sides of the Central-Southern Andes. In this presentation we proposea biogeography hypothesis for their major clades and explore the evolutionary history of their ecological characters (e.g. modes oflife). We used a phylogeny of 11 Octodontids. The distributional ranges were estimated from Nature Server Database and geographicalregions were based on WWF Ecoregions. We used DIVA to identify putative ancestral areas for each node. This, together with thedivergence time estimated for this group, served to compare with geologic and climatic events, such as Andean uplift, and majorclimate changes from Plio-Pleistocene to Holocene. Parsimony ancestral reconstruction for ecological character was performedusing Mesquite. Our results show that the ancestral area (i.e. ecoregions) for the Octodontids includes: Northern Monte, Mediterraneanshrubland, central Puna and Andean steppe. Two vicariant events, related with the Andean uplift occurred during its evolution. Thefirst one split two clades, separating species of restricted lowland areas of Monte from Chilean and high mountains species ofArgentina. 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 wascharacterized by more recent dispersion events. Terrestrial habits are suggested as the ancestral character whereas fossorial habitscould be associated to “new” habitats which emerged after the Andean uplift. We highlight the role of the Andes associated andenvironmental changes in the biogeography and ecology of this lineage