Coevolution of host-phages system Coevolution of host-phages system Bacteria-phage coevolution has previously been studied and there are evidences from laboratory and natural population that coevolution maintains phenotypic and genetic diversity within microbial communities. However, it remains uncertain how the dependence of the virus on the metabolism of the host (i.e. “viral plasticity”) affects the bacteria-phage coevolution and models of host-virus systems that do not consider viral plasticity are now recognised as unrealistic. For this reason, here we study the effect of viral plasticity on the coevolution under different environmental conditions. We compared the predictions from a classical bacteria-phage model, which neglects plasticity, with those of a model modified to include viral plasticity. Moreover, we investigate how the presence of virus is affecting the evolution of the host size. Our results may contribute to a deeper understanding of the interaction between phage and bacteria, which is a strong interest in ecology (as phages alter the microbial loop) as well as in medical or agriculture fields where phages are suggested as an alternative to antibiotics. Evolutionary stable strategy (ESS) for the host (evolving on its size) and virus (evolving on its latent period) obtained for different dilution rates (w) and different input nutrient concentrations (N0) for the plastic case. For more information about the project contact Michael Heath ( email@example.com), Professor at the Department of Mathematics and Statistcs at the University of Strathclyde. For a list of the research areas in which ARCHIE-WeSt users are active please click here.