We are investigating this phenomenon using a long-term, high resolution dataset assembled in Greifensee, Switzerland, starting in 1998. Genetic data, infection status, and some morphological and life history traits have been measured on over 30,000 individual Daphnia, over the course of 12 epidemics of their parasite Caullerya mesnilli. These data are further compared with a long-term data series from monthly routine phyto-, zooplankton and lake chemistry samplings.
Additionally, in collaboration with colleagues in Germany, we have successfully extracted parasite DNA from representative rare and common clones isolated during four epidemics. Via next generation sequencing we are characterizing the genetic background of the parasite, and are thus able to investigate host-parasite interactions in unprecedented detail.