Co-evolution between bacteria and their viruses (i.e. bacteriophages) is an essential dynamic for the ecosystem. The parasitic interaction between bacteria and phages indeed allows a bacterial diversity to emerge and ensure the ecosystem function since bacteria are involved in several biogeochemical cycles. For the co-evolution to happen, both bacteria and phages have to be locally adapted to their environment. Temperature conditions largely and directly impact bacterial population and indirectly phages. As the temperature increases, bacteria growth rate increases following the metabolic theory of ecology (MTE) until a critical temperature where they drastically decrease. Because co-evolution and local adaptation are dependent to populations size, temperature should affect bacteria-phages dynamics. The objective of this study is to describe variations of bacterial local adaptation induced by both temperature and phages interactions. We then designed a probabilistic host-parasite dynamic model in order to follow the evolution of both phages and bacteria populations. Growth rates are based on the MTE relationship and trait values are attributed to every individuals. The less the distance between phage and bacterial trait values, the higher the probability of infection. We ran the model under several different population and temperature conditions.
Results/Conclusions
Thanks to the different population conditions (bacterial population evolving alone at a certain temperature, bacteria and phages population with similar trait values and populations with distant trait values) we found, according to the literature, that the presence of phages results in a decease of bacterial local adaptation. In addition, the finite growth rate per bacterial generation decreases with the increase of temperature and the presence of phages. This means that the cost of being resistant to phages is becoming higher with the temperature increase. These results open the way to explore the fundamental understanding of the underlying mechanisms of co-evolution, especially in a context a climate change.