Demory, D. | Search bioRxiv

bioRxiv2020

A thermal trade-off between viral production and degradation drives phytoplankton-virus population dynamics

Marine viruses interact with their microbial hosts in dynamic environments shaped by variations in abiotic factors, including temperature. However, the impacts of temperature on viral infection of phytoplankton are not well understood. Here we coupled mathematical modeling with experimental datasets to explore the effect of temperature on three Micromonas-prasinovirus pairs. Our model shows the negative consequences of high temperatures on infection and suggests a temperature-dependent threshold between viral production and degradation. Modeling long-term dynamics in environments with different average temperatures revealed the potential for long-term host-virus coexistence, epidemic free, or habitat loss states. Hence, we generalized our model to global sea surface temperature of present and future seas and show that climate change may influence virus-host dynamics differently depending on the virus-host pair. Our study suggests that temperature-dependent changes in the infectivity of virus particles may lead to shifts in virus-host habitats in warmer oceans, analogous to projected changes in the habitats of macro- and micro-organisms.

ecology↗

bioRxiv2019

Linking light-dependent life history traits with population dynamics for Prochlorococcus and cyanophage

Prochlorococcus grow in diurnal rhythms driven by diel cycles. Their ecology depends on light, nutrients, and top-down mortality processes including lysis by viruses. Cyanophage, viruses that infect cyanobacteria, are also impacted by light. For example, extracellular viability and intra-cell infection kinetics of some cyanophage vary between light and dark conditions. Nonetheless, it remains unclear if light-dependent viral life history traits scale-up to influence population-level dynamics. Here we examined the impact of diel-forcing on both cellular- and population-scale dynamics in multiple Prochlorococcus-phage systems. To do so, we developed a light-driven population model including both cellular growth and viral infection dynamics. We then tested the model against measurements of experimental infection dynamics with diel forcing to examine the extent to which population level changes in both viral and host abundances could be explained by light-dependent life history traits. Model-data integration reveals that light-dependent adsorption can improve fits to population dynamics for some virus-host pairs. However, light-dependent variation alone does not fully explain realized host and virus population dynamics. Instead, we show evidence of a previously unrecognized lysis saturation at relatively high virus to cell ratios. Altogether, our study represents a quantitative approach to integrate mechanistic models to reconcile Prochlorococcus-virus dynamics spanning cellular to population scales.

microbiology↗