Data from: Experimental evidence that parasites drive eco-evolutionary feedbacks

Host resistance to parasites is a rapidly evolving trait that can
influence how hosts modify ecosystems. Eco-evolutionary feedbacks may
develop if the ecosystem effects of host resistance influence selection on
subsequent host generations. In a mesocosm experiment, using a recently
diverged (<100 generations) pair of lake and stream three-spined
sticklebacks, we tested how experimental exposure to a common fish
parasite (Gyrodactylus spp.) affects interactions between hosts and their
ecosystems in two environmental conditions (low and high nutrients). In
both environments, we found that stream sticklebacks were more resistant
to Gyrodactylus and had different gene expression profiles than lake
sticklebacks. This differential infection led to contrasting effects of
sticklebacks on a broad range of ecosystem properties, including
zooplankton community structure and nutrient cycling. These ecosystem
modifications affected the survival, body condition, and gene expression
profiles of a subsequent fish generation. In particular, lake juvenile
fish suffered increased mortality in ecosystems previously modified by
lake adults, whereas stream fish showed decreased body condition in stream
fish-modified ecosystems. Parasites reinforced selection against lake
juveniles in lake fish-modified ecosystems, but only under oligotrophic
conditions. Overall, our results highlight the overlapping timescales and
the interplay of host–parasite and host–ecosystem interactions. We provide
experimental evidence that parasites influence host-mediated effects on
ecosystems and, thereby, change the likelihood and strength of
eco-evolutionary feedbacks.