Rodent diversity in an elevation gradient from grassland to pine forest in the Chihuahuan desert ecoregion in North-Western Mexico

Abstract

Diversity patterns of rodent communities across elevational ranges have been analyzed in the Chihuahuan Desert. However, detailed local variations in community composition and species turnover across these ranges are unknown. Anthropogenic pressures in a landscape differ depending on ecosystem type, and therefore, effective conservation initiatives must incorporate an understanding of where these biotic transitions occur. We estimated the rodent diversity in a prairie-to-mountain continuum of four ecosystem types in the Chihuahuan Desert: oak forest (Quercus spp.), pine forest (Pinus spp.), grasslands, and scrublands. We hypothesized that solid habitat associations of the rodent community in each ecosystem are strong drivers that differentiate community groups across ecosystem types. We speculated that the inherent differences between prairie and mountain ecosystems will likely yield a more significant species turnover than between communities within ecosystem types. We studied the rodent communities in each of the four ecosystem types during the dry, wet, and winter seasons in the Janos Biosphere Reserve in Chihuahua, Mexico, across an elevational range from 1,300 to 2,600 m asl. The grassland rodent communities were subdivided into two groups: those with and those without black-tailed prairie dogs (Cynomys ludovicianus). We estimated species richness, number of dominant species, and species turnover for each ecosystem type across the elevational range. Our study revealed that while the prairie and mountain ecosystems support two distinctly different rodent communities, there were significant differences in community composition in each ecosystem type, except the grassland communities, where the presence/absence of the prairie dogs did not appear to influence community composition. The rodent community in the scrublands was the most species-rich and included all the grassland species and a species shared with oak and pine forests. In contrast, the mountain oak and pine forests were less diverse ecosystems dominated by habitat specialists.