The High Arctic is dominated by uncharacterized, genetically highly diverse bacteriophages

Abstract

While the Earths virosphere is estimated to be in the range of 1031 viral particles, the vast majority of its diversity has yet to be discovered. In recent years, metagenomics has rapidly allowed the identification of viruses, from microenvironments to extreme environments like the High Arctic. However, the High Arctic virome is largely composed of viral sequences that have few matches to classified viruses in existing databases. Here, to bypass limitations posed by similarity-based strategies, we resorted to a paired metagenomic (DNA, n = 8) and metatranscriptomic (RNA, n = 6) approach that placed viral genes found in Lake Hazen, the worlds largest High Arctic lake, in a phylogenetic context with known viruses. We show that High Arctic viruses have undergone unique evolutionary processes characterized by high evolutionary rates, making them distinct from and more diverse than known viruses.