Coevolutionary interactions between hosts and parasites are recognised as main potential forces influencing the life-history of both antagonists. A central prediction of coevolutionary theory is the reciprocal increase in parasite virulence and host defence, acting antagonistically to shape virulence evolution. Virulence is defined as the fitness reduction of the host caused by a parasite (including here viruses, bacteria and macroparasites).
Abiotic environmental conditions such as temperature affect both parasites and hosts and are known to variably influence virulence on the short-term. However, how coevolutionary dynamics shape virulence evolution on the long-term under changing temperatures is unresolved.
Within this project we have made use of an experimental coevolution approach to study how increasing temperatures influence virulence evolution on the long-term. To answer this question, we used the ciliate Paramecium tetraurelia infected with Caedibacter taeniospiralis bacteria. Particularly, we analysed how temperature influences the reciprocal evolutionary increase in parasite virulence and host defence predicted by coevolutionary theory. The main goal of this project was to experimentally test for temperature dependent coevolutionary dynamics shaping virulence evolution to better understand how host-parasite interactions change in a highly variable world.
This project was associated to the Priority Programme "Host-Parasite Coevolution - Rapid Reciprocal Adaptation and its Genetic Basis" of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) and part of the PhD thesis of Eike Dusi (Institute of Hydrobiology, TU Dresden), performed in close cooperation with Oliver Kaltz (Institut des Sciences de l'Evolution, CNRS, Université Montpellier 2, France).