Genomic and Ecological Flexibility Shape the Global Distribution of a Black Fungus.

Black fungi are among the most stress-resistant organisms known, yet the genetic and ecological foundations of their extraordinary resilience remain poorly understood. This study explores the adaptation strategies of the melanised fungus Elasticomyces elasticus by integrating genomic and ecological data. To uncover the mechanisms of adaptation, we combined whole-genome sequencing, functional annotation, environmental metadata, and large-scale soil metabarcoding analyses. Phylogenomic approaches were employed to delineate evolutionary lineages and assess ploidy levels. The results revealed that the global distribution of Elasticomyces phylotypes is primarily influenced by temperature, UV radiation, and soil organic carbon, suggesting that different phylotypes have evolved heterogeneous strategies for stress resistance. Comparative genomic analyses identified a set of 'sentinel pathways,' notably glutathione metabolism and nucleotide biosynthesis, which were enriched in strains inhabiting the most extreme environments and showed significant correlations with abiotic stressors such as aridity and UV exposure. Furthermore, phylogenomic reconstructions uncovered two independent diploid lineages associated with the harshest environments, pointing to diploidisation as a potential adaptive mechanism to cope with multiple stressors. Overall, the integration of genomic and ecological perspectives provides new insights into how black fungi persist at the edge of habitability. The study highlights specific pathways and genomic traits that underpin resilience to extreme conditions, offering implications that extend beyond terrestrial ecology.