Abstract
Ice-free soils of continental Antarctica host simplified but highly specialized biological communities, providing a natural laboratory to test ecological theories of community assembly under extreme environmental constraints. We investigated the diversity, spatial organization, and assembly processes of bacterial and fungal communities across 11 localities spanning a 4 ◦ latitudinal gradient in Victoria Land, Antarctica and explored faunal and protozoan diversity across 5 of these localities. Using DNA metabarcoding (16S rRNA, ITS2, and COI markers) combined with detailed soil physicochemical analyses, we compared community–environment associations and deviations from null-model expectations across kingdoms. Bacterial communities exhibited spatial differentiation among localities, and significant correlations with key edaphic variables, particularly soil conductivity, texture, pH, and nutrient content. Their co-occurrence networks were well connected and modular, and null model analyses yielded significantly positive standardized effect sizes, indicating greater compositional differentiation than expected under the null model. The more limited COI dataset suggested similar patterns for faunal and protozoan communities, although these results should be interpreted cautiously. In contrast, fungal communities showed weak and inconsistent associations with bulk soil properties, diffuse and fragmented network structures, and standardized effect sizes close to zero. Although some stress-tolerant fungal orders (e.g., Eurotiales, Hypocreales) displayed significant correlations with edaphic var iables, these patterns were not reflected in consistent community-level trends. Our results reveal differences in community-level patterns across different kingdoms within the same extreme environment. This finding cautions against assuming uniform environmental control across soil biota and highlights potential kingdom-specific sensitivities to abiotic constraints, with important implications for pre dicting ecosystem responses to environmental change in Antarctic deserts.