Aeolian microbial dispersal limitation to Antarctica

The extent to which isolated Antarctic terrestrial microbial communities may be influenced by aeolian immigration is an enduring enigma in microbial ecology. Highly specialised endemic communities display strong allopatric signals and yet microbial dispersal is conventionally viewed as occurring across inter-continental distances. Establishing the extent to which Antarctic communities are connected to the global system via aeolian dispersal has key relevance to predicting potential response of threatened polar ecosystems to environmental change. Here we describe aeolian and soil microbial diversity and identify that recruitment to soil communities cannot be explained by aeolian input alone. Airborne bacteria and fungi above the boundary layer as well as in near-ground aerosols comprised a highly specific reservoir that displayed selection for radiation- and desiccation-tolerant taxa. Microbial composition at high elevation habitats poorly suited to microbial colonisation closely mirrored aeolian diversity. Conversely, valley floor locations where extensive microbial communities developed under moisture sufficiency were distinct from aerosols. Antarctic aeolian and soil communities were almost exclusively derived from local microbial reservoirs and inter-continental immigration of taxa from the nearest non-polar landmass was negligible. These findings provide the first empirical support for dispersal limitation as a major driver of endemism in Antarctic microbial communities, we propose that resilience in this system is facilitated by aeolian dispersal from localised and ephemerally moisture sufficient refugia.