Soil biodiversity in the Atacama Desert shows distinct patterns at different diversity levels

Species diversity and distribution, in relation to how they interact with their environment has for long been a major focus of ecological research. Particularly for soil ecosystems, information about geographical patterns of biota is scarce despite the primordial role of soils as ecosystem service providers. The Atacama Desert, the driest non-polar desert on earth, where water is scarce, high salinity patches are frequent and high concentrations of metals are present in water bodies, only specialised taxa can survive. This desert supports some microbial life-forms, plant, vertebrates. Above ground invertebrates have also been reported to occur throughout its extension, but its soils have not been comprehensively analysed. By studying the Atacama as a system with different extreme habitats we aim to better understand and predict resilience of soil organisms in times of global aridification. Nematodes are one of the most important groups of soil organisms in terms of numbers and biodiversity. Here, we investigated diversity of soil nematodes at the genetic, taxonomic, community and life-cycle levels in the Atacama. We find distinct patterns in their assemblages along the different habitats in the desert: dune systems, high altitude mountains, saline lakes, river valleys and fog oases, characterizing some desert soil habitats as stable systems and others as disturbed. We also find that distribution of asexual taxa appears to be in the marginal ranges of high altitudes, and that the distribution of genera richness in the Atacama increases towards the south following a latitudinal diversity gradient, as well as with increasing precipitation. Our work shows that even under extreme environmental conditions healthy soil communities can persist, but we see indicatives of local degradation due to aridification during global change.