Microbial dispersal limitation to isolated soil habitats in the McMurdo Dry Valleys of Antarctica

Abstract

Dispersal is a critical yet poorly understood factor underlying macroecological patterns in microbial communities. Airborne microbial transport is assumed to occupy a central role in determining dispersal outcomes and extra-range dispersal has important implications for predicting ecosystem resilience and response to environmental change. One of the most pertinent biomes in this regard is Antarctica given its geographic isolation and vulnerability to climate change and human disturbance. Here we report the first characterisation of microbial diversity in near-ground and high-altitude air above a typical Antarctic Dry Valley as well as that of underlying soil microbial communities. We found that persistent airborne inputs were unable to fully explain local soil community assembly. Comparison with airborne microbial diversity from non-polar sources suggests that strong selection occurs during atmospheric transport resulting in regionally isolated airborne inputs and highly specialized soil communities where fungi displayed greater isolation than bacteria from non-polar sources. Overall microbial communities from this isolated Antarctic ecosystem displayed limited connectivity to the global microbial pool. Our findings provide critical insights to forecast the potential outcomes for microbial communities of climate change-mediated shifts in air circulation to the Dry Valleys, the largest ice-free region of Antarctica.