CONICET | Buscador de Institutos y Recursos Humanos

Much of South America consists of an extra-ordinary diversity of arid and semiarid regions, characterized by high degrees of mammal endemism. The latter is the result of a complex interplay between history of place (geological events) and history of lineages (speciation, extinction, dispersal). In this review, we characterize the structure of the small mammals of South American drylands, focusing specifically on small- and medium-sized Monte Desert mammal assemblages, particularly marsupials and rodents at regional and local scales, with comments on community ecology attributes, habitat, food utilization, responses to disturbances, and conservation. Major findings at different scales include: the distinctiveness of South American dryland mammal assemblages (e.g., 86% of the species less than 500 g occur in only one region); the richness of highland Altiplano desert supporting the role of the high Andes as a radiation center of small mammals; the heterogeneity of the Monte Desert at regional and local scales enclosing a variety of topographic, climatic, and vegetational features, and a diverse composition of small mammals; the occurrence of small mammals across all major Monte Desert macrohabitats (e.g., Prosopis woodlands, Larrea shrublands, sand dunes) at local scales although at variable densities; synchronous seasonal and annual population fluctuations among its small mammal species, but with high variability between years ; idiosyncratic organization of small- and medium-sized mammal assemblages through segregation of habitat and food niche resources; differential responses of mammal assemblages to human-induced disturbance, according to ecomorphological attributes and niche requirements; and the importance of a landscape mosaic of grazed and protected areas for maintenance of biodiversity. Thus, the heterogeneity of South American aridlands with diversity of small mammals in a variety of habitats deserves more detailed studies on biogeography, systematics, ecology, physiological adaptations, and behavioral ecology. These studies will provide important baseline information to amplify our understanding of the major common elements of desert mammal ecology, as well as strengthen the biological basis for their conservation

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