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As human activities continue to impact the climate and ecosystems of our planet, researchers are turning to the past to understand potential future scenarios induced by climate change. Glaciers, often referred to as Earth’s natural freezers, contain invaluable records of historical climate and ecological data, including the presence of viruses.
Our team, comprising microbiologists and paleoclimatologists, investigates ancient microorganisms, particularly viral entities preserved in glacial ice. Collaborating with experts like Lonnie Thompson and Virginia Rich at the Ice Core Paleoclimatology group at The Ohio State University, we focus on the interaction between viruses and their environments as preserved in ice cores from the Guliya Glacier in the Tibetan Plateau.
Our recent research has decoded viral communities from the Guliya ice core, revealing how these viruses have adapted across the last 41,000 years in relation to climate shifts. By mapping the genetic structures of ancient viral communities to specific climatic conditions captured within the glacier, we have uncovered insightful correlations.
Deciphering ancient viral genes
Utilizing metagenomic techniques, we reconstructed viral genomes from nine distinct periods in the Guliya ice core. These time frames reflect three significant climatic transitions from cold to warm periods, presenting an extraordinary chance to examine how viral populations have evolved alongside variations in climate.
Our findings revealed genomes indicative of the existence of up to 1,705 distinct virus species, significantly expanding the catalogue of ancient glacier-preserved viruses by more than fifty times.
Intriguingly, only about a quarter of the viral species identified corresponded with any previously documented viruses from extensive global metagenomic datasets. Most of the shared species were also found in the Tibetan Plateau region, which hints at the local origins of some viruses within the glacier while highlighting a gap in the databases that document glacial viruses.
The discovery allowed us to narrate the evolutionary stories of these viruses.
However, it is crucial to acknowledge that the glacier ice, which serves as a historical archive, is rapidly disappearing.
One significant outcome of our research is the observation that viral communities displayed marked variations between cold and warm periods. The emergence of a distinct viral community correlates with the climatic transition approximately 11,500 years ago, marking the shift from the Last Glacial Maximum to the Holocene epoch.
This variation indicates that climatic conditions directly influence the diversity of viral populations, possibly due to external viruses being transported by changing atmospheric patterns and the selection pressures exerted by fluctuating temperatures.
To further explore viral-host dynamics, we employed computational models to analyze the relationship between viral genomes and other microbial genomes present in the ice core. Our study showed that these viruses consistently targeted Flavobacterium, a bacterial lineage abundant in glacier regions.
Additionally, our findings revealed that these viruses are adept at “borrowing” genes from their hosts, enabling them to manipulate the hosts’ metabolic processes. We identified 50 auxiliary metabolic genes tied to various vital functions, such as the production and degradation of vitamins, amino acids, and carbohydrates. The prevalence of these genes across all nine time intervals suggests that they play a crucial role in enabling host organisms to withstand the extreme conditions found at glacier surfaces, thus enhancing viral survival.
This interplay indicates that viruses do more than simply infect and kill cells; they influence the fitness of their hosts, affecting their survival resilience in harsh glacial environments.
Insights into climate change adaptations
The implications of our research shed light on how life forms, especially viruses, have coped with significant climatic changes over tens of thousands of years.
Examining these ancient viral interactions offers a unique vantage point for both virology and climate science. A better understanding of how past viral populations adapted to climate changes can provide critical insights into current viral responses to the ongoing climate crisis.
In summary, glacier ice continues to serve as an essential reservoir of microbial history, preserving intricate details on the interactions of life over time as temperatures rise and conditions change, particularly in light of the rapid depletion of these ice reserves.
More information: Zhi-Ping Zhong et al, Glacier-preserved Tibetan Plateau viral community probably linked to warm–cold climate variations, Nature Geoscience (2024). DOI: 10.1038/s41561-024-01508-z
Source
phys.org