Global Distribution Patterns of Dark Matter Fungi in Cold Seep: A Metagenomic Meta-Analysis.

Deep-sea cold seep ecosystems, known for their unique geochemical niches and chemosynthetic communities, harbor numerous "dark matter fungi (DMF)" that remain understudied compared to their bacterial and archaeal counterparts. Integrating 105 metagenomic datasets from 12 global cold seep sites, this study systematically elucidated the diversity, biogeography, and assembly mechanisms of cold seep fungal communities. Our analysis revealed highly diverse and abundant fungi, spanning 21 phyla and 928 genera, characterized by the absolute dominance of Ascomycota and a pervasive presence of unclassified DMF. Crucially, the fungal communities exhibited significant geographical and seep-type heterogeneity, with peak abundance notably in methane seep environments. Further analyses revealed that fungal community diversity and structure are influenced by both spatial and biological factors. Moreover, assembly exhibits multi-scale characteristics: dispersal limitation is the primary determinant globally, while local-scale structure is jointly driven by environmental variables and biological interactions with key chemosynthetic genes. These findings establish the macro-biogeographical pattern of deep-sea cold seep fungi, underscoring their tight coupling with core energy metabolism and providing essential data for future research and potential utilization.