Parasites driving host diversity: incidence of disease correlated with Daphnia clonal turnover

According to the Red Queen hypothesis, clonal diversity in asexual populations could be maintained by negative frequency-dependant selection by co-evolving parasites. If common clones are selected against and rare clones gain a concomitant advantage, we expect that clonal turnover should be faster during parasite epidemics than between them. We tested this hypothesis exploring field data of the Daphnia – Caullerya host-parasite system. The clonal make-up and turnover of the Daphnia host population was tracked with high temporal resolution from 1998 until 2013, using first allozyme markers and later microsatellite markers. Significant differences in the clonal composition between random and infected sub-samples of Daphnia populations were detected on six of seven tested occasions, confirming genetic specificity of the host-parasite interaction in this system. We used time series analysis to compare the rates of host clonal turnover to the incidence of parasitism, and found that Caullerya...