Data from: Consequences of divergent temperature optima in a host-parasite system

It was suggested that parasite infections become more severe with rising
temperature, as expected during global warming. In ectothermic systems,
the growth of a parasite and therefore its reproductive capacity is
expected to increase with temperature. However, the outcome of the
interaction depends on the temperature optima of both host and parasite.
Here we used experimental infections of three-spined stickleback fish
(Gasterosteus aculeatus) with its specific tapeworm parasite
Schistocephalus solidus to investigate in detail the temperature optima
for both host and parasite. We analyzed the fitness consequences thereof,
focusing on growth and immunity of the host, and growth and offspring
production of the parasite as fitness correlates. We checked for potential
differences among populations, using the offspring of hosts and parasites
derived from four study sites in Iceland, Germany and Spain that differ in
average annual temperature ranging between 4.8 °C and 18.4 °C. We found
differences in temperature optima of host and parasites that were quite
consistent across the populations: while sticklebacks grew faster and had
higher immune activity at low temperatures, the parasites did not even
grow fast enough to reach sexual maturity in these conditions. By
contrast, with increasing temperatures, parasite growth, egg production
and offspring hatching increased strongly while host immunity and growth
were impaired. Our results show that divergent temperature optima of hosts
and parasites can have drastic fitness consequences and support the
expectation that some parasites will benefit from global warming.