Glacier-preserved Tibetan Plateau viral community probably linked to warm–cold climate variations

Glaciers archive time-structured information on climates and ecosystems, including microorganisms. However, the long-term ecogenomic dynamics or biogeography of the preserved viruses and their palaeoclimatic connections remain uninvestigated. Here we use metagenomes to reconstruct viral genomes from nine time horizons, spanning three cold-to-warm cycles over the past >41,000 years, preserved in an ice core from Guliya Glacier, Tibetan Plateau. We recover genomes of 1,705 approximately species-level viral operational taxonomic units. Viral communities significantly differ during cold and warm climatic conditions, with the most distinct community observed ~11,500 years ago during the major climate transition from the Last Glacial Stage to the Holocene. In silico analyses of virus–host interactions reveal persistently high viral pressure on Flavobacterium (a common dominant glacier lineage) and historical enrichment in the metabolism of cofactors and vitamins that can contribute to host adaptation and virus fitness under extreme conditions. Biogeographic analyses show that approximately one-fourth of Guliya viral operational taxonomic units overlap with the global dataset, primarily with the Tibetan Plateau metagenomes, suggesting regional associations of a subset of the Guliya-preserved viruses over time. We posit that the cold-to-warm variations in viral communities might be attributed to distinct virus sources and/or environmental selections under different temperature regimes.

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