Mortality and coexistence time both cause changes in predator-prey co-evolutionary dynamics

All organisms are sensitive to the abiotic environment, and in multispecies communities a deteriorating environment increasing mortality and limiting coexistence time can cause ecological changes. When interaction within the community is changed this can impact co-evolutionary processes. Here we use a mathematical model to predict ecological and evolutionary changes in a simple predator-prey community under different mortality rates and times of coexistence, both controlled by various transfer volume and transfer interval. In the simulated bacteria-ciliate system, we find species densities to be surprisingly robust under changed mortality rates and times both species coexist, resulting in stable densities. Confirming a theoretical prediction however, the evolution of anti-predator defence in the bacteria and evolution of predation efficiency in ciliates relax under high mortalities and limited times both partners interact. In contrast, evolutionary trajectories intensify when global mortalities are low, and the predator-prey community has more time for close interaction. These results provide testable hypotheses for future studies of predator-prey systems and we hope this work will help to bridge the gap in our knowledge how ecological and evolutionary process together shape composition of microbial communities.