Distribution of Microbial Generalists and Habitat Specialists in Soils Along a Climate Gradient in the Chilean Coastal Cordillera

Abstract Background: Recent studies have made significant progress in understanding how microbial composition varies across the major terrestrial biomes. However, they neglected large-scale environmental gradients and a defined set of global environmental predictors, which are applicable within biomes and across gradients, are elusive. We identified the soil microbial community composition on a broad continental scale along the Chilean Coastal Cordillera based on the generalist-specialist concept. Thereby, encompassing surface and subsurface soils from arid, semi-arid, mediterranean, and humid-temperate climate conditions.Results: Our results showed that soil communities from different climate regions are composed of the same subset of taxonomic groups. We further identified generalists, comprising taxa that predominated in all four regions, and habitat specialists that predominated in one or two regions only. We obtained higher proportions of habitat specialists (34 groups) than generalists (22 groups) with an increase of the generalist-to-specialist index along our gradient from North to South. The arid climate region revealed a unique hotspot of microbial specialization (60.1%). Contrary, the mediterranean and semi-arid regions featured mainly boundary-crossing specialists (35.5%).Conclusions: Our study supports that species sorting in response to local environmental factors is a key determinant of microbial community composition and further, the degree of microbial specialization can potentially be linked to the overall ecosystem stability.