High life history diversity within a single genus of algal viruses

Abstract

Microbial viruses are key players in aquatic ecosystems, where they control host populations and affect nutrient flow. The impact of these viruses can be understood through their life history traits, which are used to parameterize ecological models and infer evolutionary strategies. However, most existing data on microbial virus traits come from highly divergent strains. Very little is known about the trait diversity of closely related viruses, opening the critical question: can unknown viral traits be extrapolated from those of known strains? To answer this question, we quantified the life history diversity of related aquatic microbial viruses in unprecedented detail. We measured nine life history traits in 34 strains belonging to the phytoplankton-infecting genus Chlorovirus. Chloroviral traits varied 5- to 77-fold across strains, in some cases rivaling the known trait range for all phytoplankton viruses. Contrary to expectations, only specific infectivity was predictive of viral growth and there was no evidence of life history trade-offs. Our results suggest that more detailed studies of viral diversity could change our understanding of their function in aquatic ecosystems. More broadly, we show that known virus strains may not be representative of their relatives.