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Abstract

Infectious diseases are omnipresent and in the research field of epidemiology the emergence, incidence, distribution, persistence and possible control of diseases are of special interest. Research in experimental evolution can be crucial to get further insights in these subjects and to better understand infectious diseases and its dynamics. We experimentally studied the eco-evolutionary effects on infectious disease dynamics in a coevolving host-virus system consisting of the asexual reproducing, unicellular green algae Chlorella variabilis and its hostspecific dsDNA Virus, the Chlorovirus Pbcv-1. We established a novel system of two connected batch cultures (patches) to ascertain whether and how ecological and evolutionary dynamics might interfere in a spatial structured system. After infection of the algae population, the population density decreases rapidly, whereas the virus population density increased. Due to lack of hosts the virus populations decreased over time and the algae populations recovered slowly after some time of infection (25.87 ± 2.99 days), followed by a repeated decrease of algae population and an increase of virus population. Using time-shift experiments, we tested whether and when resistance of algae to virus evolved, or vice versa whether and when the virus counter adapted to the host. The time-shift experiments showed a rapid evolution of resistance of algae populations within approximately four days after infection with virus. Most importantly, our study revealed that spatial structure has a profound impact on the eco-evolutionary effects and therefore on the infectious disease dynamics in natural populations. In this context spatial heterogeneity or patchiness, which is common in nature, can have a major influence on the infectious disease dynamics.