| Summary: | The McMurdo Dry Valleys of Antarctica are an abiotically driven ecosystem characterized by having a very simple trophic structure dominated by microbial communities, whose diversity is shaped by extreme abiotic gradients, particularly extreme aridity and oligotrophy. Regional isolation and dispersal limitations have concurrently led to the emergence of heterogeneous microbial communities with highly localized dominant taxa across the region. These taxa were selected based on specialized genetic and physiological adaptations accumulated during long-term isolation, which conferred an advantage to endure the physical and chemical stress. Models predict that over the coming decades, climate change will trigger hydrological changes in the system with potential consequences for its microbial communities and, subsequently, ecosystem-level processes. The capacity of the Antarctic microbiome to absorb change while maintaining its structural and/or functional attributes will determine the extent to which predicted environmental changes will threaten the system's stability. This research starts by developing and validating a space-for-time sampling approach using variations in geochemical factors that follow alterations in water availability as time progresses and to which biological communities respond. This approach was replicated across the six major lakes in the Wright and Taylor valleys, and builds on previous examples of environmental gradients, which used arbitrary distance-based metrics as sampling design, incorporating significant yet uncharacterized in situ geochemical variability. The approach developed here enabled the acquisition of a comprehensive dataset that predicts, with confidence, that future hydrological changes will significantly alter the composition and diversity of microbial communities historically adapted to arid and oligotrophic conditions. The latter will result in significant changes in the metabolic activity of pathways associated with carbon, nitrogen, phosphorous and sulphur cycles, with an ...
|
|---|