Parasite-induced gigantism in a snail: a host adaptation?

摘要: I experimentally tested the hypothesis that parasite-induced gigantism in molluscs may be a host adaptation by increasing host's probability of outliving an infection. exposed juvenile pulmonate snails from two populations hermaphrodite Lymnaea peregra to infections with trematode Diplostomum phoxini. Only one snail studied is naturally contact this parasite (P + ) and other not - ). phoxini induced only P snails. Furthermore, showed lower mortality compared but infected did lay eggs before they died. These results are agreement three out four predictions derived as adaptation. The fourth prediction, some should survive long enough outlive infection reproduce, was met. My do directly support idea adaptive value for L. suggest unlikely purely This study cannot exclude alternative non-adaptive side-effect