Media release

From: Springer Nature

The reconstruction of viral genomes, preserved in an ice core from the Tibetan Plateau, from nine intervals over the past 41,000 years, is reported in a paper published in Nature Geoscience. The findings show that viral community composition changed with climate fluctuations and may aid our understanding of how past environmental change shaped microbial ecosystems.

Glacial ice can preserve microbes, including viruses and bacteria, and sampling this ice can present an opportunity to assess the factors that influence the diversity of these microbial communities over hundreds to thousands of years. Being able to assess ecological change across long timescales can help establish baselines for understanding how microbial communities will adjust to ongoing climate change.

Zhi-Ping Zhong and colleagues used DNA extraction and metagenomic methods to characterise viruses preserved in a 310-metre-long ice core drilled from the Guliya Glacier on the Tibetan Plateau. They performed genomic analysis on nine samples of the ice, each representing a different time interval, with the oldest dating back to the Last Glacial Period, at least 41,000 years ago. The authors recovered genomes for 1,705 species-level viral taxonomic units. They indicate that viral communities differ between cold climate periods and warm periods, with the most distinct community being identified at the climatic transition between the Last Glacial Stage and the Holocene, about 11,500 years ago. Further analysis suggests that extreme conditions may have led to the viruses developing enriched metabolisms to allow them to survive extreme environments.

The authors propose that the variation in the ice core viral communities may be due to viruses being blown in from another geographic source. Likewise, some variation may be attributed to only certain viruses surviving the environmental conditions within the ice itself.