[biorxiv.org] Viruses are the most abundant known biological entities in the ocean and play central role in microbial ecology. However, the patterns and drivers of their biogeographic distribution across global ocean remain poorly understood. Here, we conducted large-scale metagenomic analysis of 514 samples from globally-distributed hydrothermal vents and the pelagic ocean to examine the biogeography of giant viruses, a widespread viral group in the ocean.
Editor’s note: When we start to mount Astrobiology missions to explore ocean worlds we’ll need ways for our robotic submersibles to observe and interact with whatever life forms they may encounter. It is highly probable that we will discover life that is both similar and utterly different than Earth life. This is especially important in ‘extreme’ environments on out home world where old notions of life have been totally revised – in many cases revealing possible avenues for its origin on Earth.The better that we learn how to catalog the immense diversity of life here – the better prepared we will be to embark on a similar task on other inhabited worlds.
We identified 279 putative giant virus populations from hydrothermal vents and 56 populations were broadly distributed across hydrothermal vents. Vent-derived giant viruses are also present in the global pelagic ocean showing an “everything is everywhere” biogeographic pattern.
We identified the mechanistic processes governing this global distribution of giant viruses and found that horizontal passive transport, mediated by hydrothermal plumes, is likely a major mechanism that drives the global connectivity of vent-derived giant viruses. Additionally, environmental selection appears to shape viral distributions within high-temperature vent habitats, as giant viruses encoding heat-shock proteins were enriched in these environments.
Overall, this study identified the key process that sustain global-scale ecological connectivity for viruses between hydrothermal vents and pelagic ocean and demonstrates that a classic microbial biogeography paradigm, “everything is everywhere, but the environment selects” applies to marine giant viruses.
World map showing the global-distribution of metagenomic sampling locations analyzed in this study. Parentheses indicate the type of vent environment: d (diffuse fluid), h (hydrothermal fluid), p (plume), sed (sediment), and s (sulfide deposit). — biorxiv.org
Bioinformatic pipeline utilized in this study. Schematic workflow from raw metagenomic reads to NCLDV contigs database and analysis from 514 metagenomic samples including three samples collected in this study and 511 samples previously collected across 6 geographically-distinct vents sites. — biorxiv.org
Phylogenetic analysis of the vent-derived NCLDV contigs. Phylogenetic tree (IQ740 TREE model: LG+R7) of 279 NCLDV contigs based on a concatenated alignment of ten NCLDV marker genes (A32, PolB, VLTF3, SFII, mcp, RNR, RNAPS, RNAPL, D5, TFIIS), visualize on iTOL [69]. The inner ring indicates the hydrothermal vent location from which each contig was assembled. The middle ring indicates widely-distributed giant virus contigs, defined by their presence in ≥4 out of the six vent systems and the outer ring indicates the order-level taxonomy of the NCLDV contigs, as identified through marker gene based homology with the giant virus database [62].– biorxiv.org
The biogeography of hydrothermal vent giant viruses across the global ocean, biorxiv.org
Astrobiology, Genomics, Extremophiles, Bioinformatics,
