Species interactions lay along a parasitic-mutualistic continuum where cost and benefits change by the interplay of ecological and evolutionary processes. Therefore, mutualistic microbe-host associations to fight pathogens can be a temporal defence strategy that might become costly for the host driving the community to extinction if host is overexploited by both virus and virophage. We use a marine heterotrophic flagellate protected by a virophage (which can integrate into the host genome) against viral infections. First, we studied the role of microbial-mediated protection for species coexistence. Second, we tested if host-virophage interactions evolved towards parasitism. We maintained a microbial community of host-virus-virophage in chemostats for 50 days (~200 host generations). We monitored population dynamics and selected host clones from the end of the experiment. Selected host clone traits diversified from the ancestral host populations, suggesting that they evolved during the experiment. Specifically, we detected an increase in the number of integrated virophages between ancestors and selected clones and differences in virophage reactivation in the selected host clones.

Primary Presenter: Ana del Arco, University of Konstanz (ana.del-arco@uni-konstanz.de)

Authors:

Ana del Arco, Aquatic Ecology and Evolution Group, Limnological Institute, University of Konstanz, Germany   (ana.del-arco@uni-konstanz.de)

Matthias G. Fischer, Max Planck Institute for Medical Research, Heidelberg, Germany  (matthias.Fischer@mpimf-heidelberg.mpg.de)

Lutz Becks, Aquatic Ecology and Evolution Group, Limnological Institute, University of Konstanz, Germany   (lutz.becks@uni-konstanz.de)