Caporaso_Atacama

The Atacama Desert of northern Chile is one of the driest and oldest deserts on Earth and provides an ideal location for studying environmental drivers of microbial diversity under a gradient of stable arid conditions. The objective of the current study is to exploit the unique biogeography of the Atacama Desert to characterize variability in microbial diversity along transects extending from the core hyperarid desert to the vegetated western slopes of the Andes in an effort to identify critical factors that control the alpha- and beta-diversity of arid soil microbial communities. Biogeochemical and physical profiles were generated of soils sampled along two elevational, west-east transects (1000 to 4700 meters above sea level) using Illumina MiSeq sequencing of 16S rRNA gene amplicons, geochemical analyses, and three years of climate data obtained from data loggers installed at each site. Key to this study is the identification of predictive environmental parameters that control microbial diversity in arid ecosystems and can be used to inform models evaluating the vulnerability of the basic ecosystem services provided by these communities. A strong positive correlation was observed between bacterial and archaeal alpha diversity and average soil relative humidity, as measured by phylogenetic diversity (a phylogenetic richness metric; Spearman’s rho = 0.748; p less than 0.001). Microbial diversity in the Atacama Desert is correlated with average soil relative humidity (Mantel’s r = 0.625; p = 0.0001), soil temperature high (Mantel’s r = 0.377; p = 0.0001), and electrical conductivity (Mantel’s r = 0.496; p = 0.0001), but it is not correlated with pH (Mantel’s r = 0.108; p = 0.063).