Data from: On the equivalence of host local adaptation and parasite maladaptation: an experimental test

In spatio-temporally varying environments, host-parasite coevolution may
lead to either host or parasite local adaptation. Using reciprocal
infestations over 11 pairs of plots, we tested local adaptation in the hen
flea and its main host, the great tit. Flea reproductive success (number
of adult at host fledging) was lower on host individuals from the same
plot compared to foreign hosts (from another plot), revealing flea local
maladaptation. Host reproductive success (number of fledged young) was
lower for nests infested by foreign fleas compared to controls, with an
intermediate success for nests infested by local fleas. This suggests host
local adaptation although the absence of local adaptation could not be
excluded. However, fledglings were heavier and larger when reared with
foreign compared to local fleas, which could also indicate host local
maladaptation if the fitness gain in offspring size offsets the potential
cost in offspring number. Our results therefore challenge the traditional
view that parasite local maladaptation is equivalent to host local
adaptation. The differences in fledgling morphology between nests infested
with local and foreign fleas suggest that flea origin affects host
resource allocation strategy between nestling growth and defense against
parasites. Therefore determining the mechanisms that underlie these local
adaptation patterns requires the identification of the relevant fitness
measures and life-history trade-offs in both species.