The study by Angly et al. (2006) investigates the marine viromes of four oceanic regions: the Sargasso Sea, the Gulf of Mexico, British Columbia, and the Arctic Ocean. Metagenomic analyses of 184 viral assemblages collected over a decade and representing 68 sites revealed that most viral sequences were not similar to those in current databases, indicating a distinct "marine-ness" to the viral assemblages. The global diversity was found to be very high, with an estimated number of species ranging from a few hundred thousand. Regional richness varied along a North-South latitudinal gradient, with higher diversity at lower latitudes. The marine regions had different viral assemblages, with cyanophages and a newly discovered clade of single-stranded DNA (ssDNA) phages dominating the Sargasso Sea sample, while prophage-like sequences were most common in the Arctic. Most viral species were widespread, and the differences between viral assemblages were primarily explained by variation in the occurrence of the most common viral species rather than the exclusion of different viral genomes. These findings support the idea that viruses are widely dispersed and that local environmental conditions enrich certain viral types through selective pressure. The study also highlights the importance of integrating viral and microbial metagenomes to better understand the dynamics and distribution of marine viruses.The study by Angly et al. (2006) investigates the marine viromes of four oceanic regions: the Sargasso Sea, the Gulf of Mexico, British Columbia, and the Arctic Ocean. Metagenomic analyses of 184 viral assemblages collected over a decade and representing 68 sites revealed that most viral sequences were not similar to those in current databases, indicating a distinct "marine-ness" to the viral assemblages. The global diversity was found to be very high, with an estimated number of species ranging from a few hundred thousand. Regional richness varied along a North-South latitudinal gradient, with higher diversity at lower latitudes. The marine regions had different viral assemblages, with cyanophages and a newly discovered clade of single-stranded DNA (ssDNA) phages dominating the Sargasso Sea sample, while prophage-like sequences were most common in the Arctic. Most viral species were widespread, and the differences between viral assemblages were primarily explained by variation in the occurrence of the most common viral species rather than the exclusion of different viral genomes. These findings support the idea that viruses are widely dispersed and that local environmental conditions enrich certain viral types through selective pressure. The study also highlights the importance of integrating viral and microbial metagenomes to better understand the dynamics and distribution of marine viruses.