Data from: Host developmental stage effects on parasite resistance and tolerance

Hosts can defend themselves against parasites by either preventing or
limiting infections (resistance), or limiting parasite-induced damage
(tolerance). However, it remains underexplored how these defense types
vary over host development with shifting patterns of resource allocation
priorities. Here, we studied the role of developmental stage on resistance
and tolerance in Atlantic salmon (Salmo salar). This anadromous fish has
distinct life stages related to living in fresh and sea water. We
experimentally exposed one-year old salmon, either at the freshwater stage
or at the stage transitioning to the marine phase, to the trematode
Diplostomum pseudospathaceum. Using 56 pedigreed families and multivariate
animal models, we show that developmental transition is associated with
reduced resistance, but does not affect tolerance. Furthermore, by
comparing tolerance slopes (host fitness against parasite load) based on
additive genetic effects among infected and unexposed control relatives,
we observed that the slopes can be largely independent of the infection,
that is they may not reflect tolerance. Together, our results suggest that
the relative importance of different defense types may vary with host
development and emphasize the importance of including control treatments
for more confident interpretations of tolerance estimates.