Viruses are key actors of ecosystems and have major impacts on global biogeochemical cycles. Prophages deserve particular attention as they are ubiquitous in bacterial genomes and can enter a lytic cycle when triggered by environmental conditions. We explored how temperature affects the interactions between prophages and other biological levels by using an opportunistic pathogen, the bacterium Serratia marcescens, that harbours several prophages and that had undergone an evolution experiment under several temperature regimes. We found that the release of one of the prophages was temperature-sensitive and malleable to evolutionary changes. We further discovered that the virulence of the bacterium in an insect model also evolved and was positively correlated with phage release rates. We determined through analysis of genetic and epigenetic data that changes in the bacterial outer cell wall structure possibly explain this phenomenon. We hypothezise that the temperature-dependent phage release rate acted as a selection pressure on S. marcescens and that it resulted in modified bacterial virulence in the insect host. Our study system illustrates how viruses can mediate the influence of abiotic environmental changes to other biological levels and thus be involved in ecosystem feedback loops.

All dataset files are plain text, tab-separated tabular files. R scripts are also provided to reproduce the analyses and the figures reported in the article. Those scripts can be executed using the R program (https://www.r-project.org/). A pdf file ("pipeline.pdf") is provided to give an overview of the dependencies between dataset files, R scripts, and output files.

Phage particle quantification by qPCR. Bacterial virulence estimated from survival of infected waxmoth larvae. PacBio sequencing data and other bacterial phenotypic data, based on previously published articles. All Methods are described in detail in the original paper, available as an Open Access article from https://doi.org/10.1111/mec.16638.