CONICET | Buscador de Institutos y Recursos Humanos

During the last four years I studied small mammal fauna along elevation gradients of mountain ranges in NW Argentina. The results of the direct trapping protocol used for terrestrial small mammals, reveled a hump shaped pattern of species richness along elevation. Among the several hypotheses proposed to explain this patter, that one dealing with rates of speciation lie at the core of evolutionary process. Rodents, as the more diverse group of mammals are frequently the most important part of small mammal assemblages concerning to the number of species. Additionally, rodents have shown to form quite conspicuous assemblages and therefore, seem to be particularly useful to analyze endemism patterns on mountain slopes. The concept of endemism implies geographic restriction of a taxon to a particular area; thus it is relative to geographic area under study. In this study, I considered as endemic species those which are restricted to the Aconquija and adjacent Cumbres Calchaquies mountain ranges. For this study I compiled distributional record of rodents inhabiting the eastern slopes of these mountain ranges form specimens deposited in museums and direct trapping. Then I listed species within 500m elevation belt for asses the variation of richness and endemism along the elevation gradient (500-4500m). Endemism was expressed either as the number of endemic species in each elevation belt or as the percentage of endemic species relative to the total species number in that belt. I recorded 37 species of rodents, of which 11 are endemic. Species richness showed a peak at the 1000-1500 elevation belt. The elevation pattern of endemic species was hump-shaped. For the raw number of endemic species per elevation belt the peak was located between 1500-2500m. For the percentage of endemic species per elevation belt the peak was located at the 2000-2500 elevation belt.

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