Figure 1

Parasite prevalence, host population density and number of host resting eggs in the epidemiological experiment. Means of parasite prevalence (a), of host population density (b) and of number of Daphnia ephippia (c) and their standard errors in experimental populations of the host Daphnia magna either uninfected or infected with the microsporidium Hamiltosporidium tvärminnensis. Host populations differed in their initial parasite prevalence in April 2002 (0%: n = 14, 5%: n = 10, 50%: n = 10 or 100%: n = 10), were kept outdoors and sampled regularly between 2002 and 2006.