Data from: Latitudinal patterns of phenology and age-specific thermal performance across six Coenagrion damselfly species

Using a combination of computer simulations and laboratory experiments we
test if the thermal sensitivity of growth rates change during ontogeny in
damselfly larvae and if these changes can be predicted based on the
natural progression of average temperature or thermal variability in the
field. The laboratory experiment included replicated species from
Southern, Central and Northern Europe. Although annual fluctuations in
temperature represent a key characteristic of temperate environments, few
studies of thermal performance have considered the ecological importance
of the studied traits within a seasonal context. Instead, thermal
performance is assumed to remain constant throughout ontogeny and reflect
selection acting over the whole life cycle. The laboratory experiment
revealed considerable variation among species in the strength and
direction of ontogenetic performance shifts. In four species from Southern
and Central Europe, reaction norms were steepest during early ontogeny,
becoming less steep during later ontogenetic stages (indicative of
low-temperature acclimation). In one Northern European species, the slope
of reaction norms did not change during ontogeny. In the other North
European species, reaction norms became steeper during ontogeny
(indicative of high-temperature acclimation). We had expected
high-latitude species to show strong low-temperature acclimation
responses, because they have a short flight season and inhabit a strongly
seasonal environment. Instead, we found the reversed pattern low-latitude
species displayed strong low-temperature acclimation responses and
high-latitude species displayed weak, or even reversed, acclimation
responses to low temperatures. These findings suggest that low-temperature
acclimation may be less beneficial and possibly more costly in habitats
with rapid seasonal transitions in average temperature. We conclude that
thermal performance traits are more dynamic than typically assumed and
caut ion against using results from single ontogenetic stages to predict
species' responses to changing environmental conditions.