Brum, Ignacio-Espinosa, Roux et al.
Global patterns and ecological drivers of ocean viral communities
Viruses have major impacts on Earth’s ecosystem processes through their modulation of population size, diversity, metabolic outputs, and gene flow of the most dominant organisms on Earth – microbes. In this study, the researchers establish the first global, quantitative dataset of marine viral community genomics and morphology from 43 Tara Oceans expedition samples to investigate upper-ocean marine viral community patterns and structure.
Analysis of global viral gene content through the use of protein cluster (PC) cataloging suggested that pelagic upper-ocean viral community sequence space is now well-sampled and approaches a limit of ca. 1 million PCs. Furthermore the most abundant and widespread viral populations observed in the samples lack cultured representatives, which suggests that most upper ocean viruses remain to be characterized.
This global-scale analysis of multiple parameters of marine viral communities (PCs, populations, and morphology) revealed biogeographic patterns that support a long-posited ‘seed-bank’ hypothesis whereby viral communities are passively transported on oceanic currents and structured by local environmental conditions such as temperature and oxygen concentration. Together these investigations explain how oceanic viral communities maintain high local diversity that is consistent with limited global diversity.
This study provides a picture of global upper-ocean viral communities. Improving sequencing and experimental methods are transforming the investigation of viruses in nature. Those progresses, coupled to sampling opportunities from the Tara Oceans voyage, are advancing viral ecology towards the quantitative science needed to model the nano- (viruses) and micro- (microbes) scale entities driving Earth’s ecosystems.
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