This system allowed me to manipulate the infection (horizontal/vertical) and measure the changes in the life-history of infected hosts, as well as the dynamics of the parasite inside the host. In both cases, the route of infection had a strong effect. [more]
I also investigated the effect of multiple infections. Multiple infections can affect the harm to the host plastically, through within-host parasite competition. Interestingly, this harm could increase (e.g. if competition leads to higher spore-production), or decrease (e.g. if competition results in 'chemical' warfare). By using a life-table experiment with several combinations of parasite isolates, I unravelled part of the mystery. [more]
Octosporea bayeri induces the production of males in some Daphnia magna clones. Infected Daphnia doesn't get rid the parasite when reproducing parthenogenetically (as vertical transmission is 100% efficient!, see here for details). Therefore, an infected clone will carry the parasite until it is outcompeted by uninfected clones. If the parasite cannot be transmitted from males to offspring, sex would be a 'rescue' strategy for the infected clone, whenever males mate with uninfected females. Is this then evidence for short-term advantage of sex? It might be. But male production can benefit the parasite as well, as it can over-exploit the males to produce spores and spread the infection in the uninfected part of the population. This findings open a new avenue of research in the Octosporea-Daphnia system. [more]
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last uptaded: 29.02.2008