Data from: Faster clonal turnover in high-infection habitats provides evidence for parasite-mediated selection

According to the Red Queen hypothesis for sex, parasite-mediated selection
against common clones counterbalances the reproductive advantage of
asexual lineages, which would otherwise outcompete sexual conspecifics.
Such selection on the clonal population is expected to lead to a faster
clonal turnover in habitats where selection by parasites is stronger. We
tested this prediction by comparing the genetic structure of clonal and
sexual populations of freshwater snail Potamopyrgus antipodarum between
years 2003 and 2007 in three depth-specific habitats in Lake Alexandrina
(South Island, New Zealand). These habitats differ in the risk of
infection by castrating trematodes and in the relative proportion of
sexual individuals. As predicted, we found that the clonal structure
changed significantly in shallow and mid-water habitats, where prevalence
of infection was high, but not in the deep habitat, where parasite
prevalence was low. Additionally, we found that both clonal diversity and
evenness of the asexual population declined in the shallow habitat. In
contrast, the genetic structure (based on F–statistics) of the coexisting
sexual population did not change, which suggests that the change in the
clonal structure cannot be related to genetic changes in the sexual
population. Finally, the frequency of sexuals had no effect on the
diversity of the sympatric clonal population. Taken together, our results
show a more rapid clonal turnover in high-infection habitats, which gives
support for the Red Queen hypothesis for sex.