Dispersal pathways and infection strategies within the Global Halophilic Virome

Microbial biogeography has recently attracted significant attention for its potential to provide novel ecological and evolutionary insights, with environmental connectivity emerging as a key factor in the global distribution of viruses and their hosts. Hypersaline systems, due to their geographical isolation and extreme conditions, are typically expected to exhibit low connectivity. However, reports of similar viral assemblages in geographically distant hypersaline environments suggest a higher level of connectivity than previously assumed, although the mechanisms underlying viral dispersal remain poorly understood. We hypothesized that seawater facilitates the dispersal of halophilic viruses (haloviruses). To test the hypothesis, we analyzed twenty hypersaline water samples from globally distributed sites across four continents and constructed "The Global Halophilic Virome Dataset" (GHV), containing 10 705 viral Operational Taxonomic Units (vOTUs). Additionally, we proposed a sample-adapted threshold to distinguish between "abundant" and "rare" members of the virosphere. Our findings indicate that coastal hypersaline systems harbor highly similar viral communities, whereas inland systems are dominated by endemic vOTUs, and that seawater may act as the primary carrier of halovirus dispersal. Infection strategies also varied across environments, with coastal salterns showing a lower potential for viral infection and a higher percentage of viruses with a potential integrative temperate lifestyle.