Microbes drive most ecosystems and are modulated by viruses that impact their lifespan, gene flow and metabolic outputs. However, ecosystem-level impacts of viral community diversity remains difficult to assess due to classification issues and few reference genomes. Here we establish a ~12-fold expanded global ocean DNA virome dataset of 195,728 60 viral populations, now including the Arctic Ocean, and validate that these populations form discrete genotypic clusters. Meta-community analyses revealed five ecological zones throughout the global ocean, including two distinct Arctic regions. Across the zones, local and global patterns and drivers in viral community diversity were established for both macrodiversity (interpopulation diversity) and microdiversity (intra-population genetic variation). These patterns 65 sometimes, but not always, paralleled those from macro-organisms and revealed temperate and tropical surface waters and the Arctic as biodiversity hotspots and mechanistic hypotheses to explain them. Such further understanding of ocean viruses is critical for broader inclusion in ecosystem models.
Introduction: 70Biodiversity is essential for maintaining ecosystem functions and services (reviewed by Tilman et al., 2014). In the oceans, the vast majority of biodiversity is contained within the microbial fraction containing prokaryotes and eukaryotic microbes, which represents ~60% of its biomass (Bar-On et al., 2018). Meta-analyses looking at changes in marine biodiversity show that biodiversity loss increasingly impairs the ocean's capacity to produce food, maintain water 75 quality, and recover from perturbations (Worm et al., 2006). To date, marine conservation efforts have focused on specific organismal communities, such as fisheries or coral reefs, rather than conserving whole ecosystem biodiversity. However, emerging studies across diverse sampled, global-scale, viruses-to-fish-larvae datasets (de Vargas et al., 2015; Sunagawa et al., 125 2015;Brum et al., 2015;Lima-Mendez et al., 2015;Pesant et al. 2015;Roux et al., 2016), and help establish foundational ecological hypotheses for the field and a roadmap for the broader life sciences community to better study viruses in complex communities.
Results & Discussion:The dataset. The Global Ocean Viromes 2.0 (GOV 2.0) dataset is derived from 3.95 Tb 130 of sequencing across 145 samples distributed throughout the world's oceans ( Fig. 1A and Table S3; see Methods). These data build on the prior GOV dataset (Roux et al., 2016) by increased sequencing for mesopelagic samples (defined in our dataset as waters between 150m to 1,000m) and upgrading assemblies, both of which drastically improved sampling of the ocean viruses in these samples (results below). Additionally, we added 41 new samples derived from the Tara 135Oceans Polar Circle (TOPC) expedition, which traveled 25,000 km around the Arctic Ocean in 2013. These 41 Arctic Ocean viromes were generated to represent the most significantly climateimpacted region of the ocean, and an extreme environment. N...
