The presence of the Andes produces a high variability of habitats, diversity of climates, highest richness and rise of endemic species (Pacheco et al., 2009). The diversity and richness of mammals along the altitudinal gradient change depending of the heterogeneity of the habitat and is not the same in the different taxonomic groups. The change of environmental variables determine the richness and the abundance of species. The variation of richness of the species in different altitudes has been explained by Rapoport Rule (1982) that predicts to the most richness species in lowland than highlands. This pattern has been reported also to birds and bats (Patterson et al, 1998). Contrarily, Heaney et al. (1989) found the most richness in intermediate altitudes. Also Md Nor (2001), Heaney (2001), McCain (2003, 2004) y Mena y Vázquez-Domínguez (2005) found more species of rodents and McCain (2004) and Medina et al. (2012) found more species of small mammals in the intermediate altitudes. The lack of studies in the Central Peru did not left the understanding of the patterns to local and regional scale. The objective of this research is contribute with the knowledge of the altitudinal gradient of the distribution of small non-volant mammals and research the relation between environmental factors of the species distribution.
In 2011 I evaluated an altitudinal gradient on seven localities of field sites or localities in Pampa Hermosa River, Junín, Perú at 1000 to 2850 masl. I evaluated the richness pattern of species between altitudes with a diversity analysis and the nule model. To the description of habitats, I measured 11 variables of vegetation in each transect located at 300 masl approximately.
I register 491 samples belong to 34 species, of the Didelphidae, Cricetidae and Echimyidae, . The richness was high at 300-1900 masl, however the higher diversity index was at 1300 masl (H’=1.78 and 1-D=2.47). Akodon torques is the most abundant species. The test “t” show significant difference between the diversity index of the low and high altitude (p<0,001), meanwhile, the nule model verify the effect of the medium domain with a geometric pattern. Also, I report Monodelphis gardneri as the species of the greater altitudinal range, and with the slower report in this research. Also, the accumulation curve of species shows that I registered 34 to 45 potential species.
The Analysis of Principal Components (ACP) demonstrates the correlation of each vegetation variable with the presence of species in each field site.
The effect of the mid domain shows that intermediate altitudes were the most richness field sites.
I include the rediscovery of Marmosops juninensis, a especies of marsupial recently described by Solari (2012), this report is after almost 50 years that was not registered. Also, I report the extension range of Monodelphis gardneri, before reported just between 1785 to 2800 masl and now is known to occur also at 1000 masl.
Project 0905276 location - Peru, South America