Viruses in Glacial Environments

Viruses play a central role in glacial microbial communities. Prokaryotes in glacial environments support surprisingly large viral communities, which, in turn, have a considerable impact on the prokaryotic communities. Through the lysis of host cells and by lowering the growth efficiency of prokaryotic communities, viruses substantially alter the carbon cycling in glacial environments. Despite many similarities with viruses in other habitats, the unique characteristics of glacial environments have accentuated certain features in glacial viruses and their interactions with their hosts, e.g. low viral decay rates in supraglacial viruses as a mechanism for overcoming low host contact rates in systems with low prokaryotic abundances, virus-specific temperature adaptation that differ from that of the host, and virus-mediated transfer of CRISPR arrays that confer immunity against superinfection. Current literature suggests that viral communities in glacial environments are as genetically diverse as those in other environments and, with recent technological advances in environmental genomics and bioinformatics, we are posed to tackle the next great challenge in viral ecology of identifying and quantifying the dynamics of individual virus–host pairs in environmental samples.