Mammals in South American drylands: faunal similarity and trophic structure

Abstract

We compared the fauna of small mammals (less than 500 g body weight) among five major South American drylands (Atacama, Altiplano, Monte, Patagonia and Caatinga) and found considerable heterogeneity and distinctiveness in species richness and composition between these biomes. From a total of 89 recorded species, 76 of them are restricted to only one of these drylands. The highland desert, or Altiplano, is the biome with the highest number of species. Despite the marked differences in the composition of the mammalian fauna, the trophic structure shows a rather consistent pattern: herbivores are the most important trophic group in all drylands. This consistency seems to be more the result of phylogenetic inertia than of similar ecological processes. Our results are compared with recent studies on desert small mammals across continents.

The mammals of the Monte Desert revisited

“…Moreover, when this is coupled with macroecological analysis at different scales (e.g. regional vs. local) (Kelt et al, 1996(Kelt et al, , 2000Ojeda et al, 2000) the identification of patterns (if any), is even more complicated.…”

“…Andean drylands played a major role in the cladogenetic process of sigmodontine rodents (Reig, 1986), and this is reflected in their high species richness and in the number of endemics (e.g. rodents, Hershkovitz, 1972;Marquet, 1994a, b;Ojeda et al, 2000;Reig, 1986). The diversity of small mammals decreases in the lowland deserts on both sides of the Andes.…”

Biological interactions at different spatial scales in the Monte desert of Argentina

“…In the Monte Desert, the importance of herbivory by large rodents contrasts with the North American or African deserts where the native ungulate guild is more diverse than in South America (Bucher, 1987;Kerley, 1992;Ojeda et al, 2000). Although most mammals feed on a wide range of grass and shrub species, they do not consume the dominant creosote bush of the Monte (Larrea spp.…”

Patterns of diversity of the Monte Desert small mammals across multiple spatial scales

“…When considering the habitat-patch scale (0.16e1 ha), there are about three species (Kelt et al, 1996;Tabeni and Ojeda, 2005), while at the biome scale (more than 100,000 km 2 ), mammal richness is the highest in South American drylands because of the large number of endemic species (Mares, 1992). Despite the wide range of spatial scales at which small mammal diversity has been analyzed (Brown and Kurzius,1987;Kelt et al, 1996;Shenbrot et al, 1999;Ojeda et al, 2000;Corbalán and Ojeda, 2004;Tabeni and Ojeda, 2005;Haythornthwaite and Dickman, 2006), studies relating diversity at more than two different scales are very scarce. Some studies focus on relationships between habitat patch and landscape scales, while others focus on regional to continental scales.…”