| Affiliation: | 1 Department of Biology, San Diego State University, San Diego, California, United States of America, 2 Computational Science Research Center, San Diego State University, San Diego, California, United States of America, 3 Department of Mathematics, San Diego State University, San Diego, California, United States of America, 4 Center for Microbial Sciences, San Diego State University, San Diego, California, United States of America, 5 Fellowship for Interpretation of Genomes, Burr Ridge, Illinois, United States of America, 6 University of California Santa Barbara, Santa Barbara, California, United States of America, 7 Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, British Columbia, Canada, 8 Argonne National Laboratory, Argonne, Illinois, United States of America, 9 Bermuda Biological Station for Research, St. George's, Bermuda, 10 Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada, 11 Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada |
| Abstract: | Viruses are the most common biological entities in the marine environment. There has not been a global survey of these viruses, and consequently, it is not known what types of viruses are in Earth's oceans or how they are distributed. Metagenomic analyses of 184 viral assemblages collected over a decade and representing 68 sites in four major oceanic regions showed that most of the viral sequences were not similar to those in the current databases. There was a distinct “marine-ness” quality to the viral assemblages. Global diversity was very high, presumably several hundred thousand of species, and regional richness varied on a North-South latitudinal gradient. The marine regions had different assemblages of viruses. Cyanophages and a newly discovered clade of single-stranded DNA phages dominated the Sargasso Sea sample, whereas prophage-like sequences were most common in the Arctic. However most viral species were found to be widespread. With a majority of shared species between oceanic regions, most of the differences between viral assemblages seemed to be explained by variation in the occurrence of the most common viral species and not by exclusion of different viral genomes. These results support the idea that viruses are widely dispersed and that local environmental conditions enrich for certain viral types through selective pressure. |
