Contribution of genetic versus plastic responses to adaptive patterns in a widespread butterfly along a latitudinal cline

Understanding how organisms adapt to complex environments is a central
goal of evolutionary biology and ecology. This issue is of special
interest in the current era of rapidly changing climatic conditions. Here,
we investigate clinal variation and plastic responses in life history,
morphology, and physiology in the butterfly Pieris napi along a
pan-European gradient by exposing butterflies raised in captivity to
different temperatures. We found clinal variation in body size, growth
rates and concomitant development time, wing aspect ratio, wing
melanisation, and heat tolerance. Individuals from warmer environments
were more heat-tolerant, had less melanised wings and a shorter
development but still they were larger than individuals from cooler
environments. These findings suggest selection for rapid growth in the
warmth and for wing melanisation in the cold, and thus fine-tuned genetic
adaptation to local climates. Irrespective of the origin of butterflies,
the effects of higher developmental temperature were largely as expected,
speeding up development, reducing body size, potential metabolic activity,
and wing melanisation, while increasing heat tolerance. At least in part,
these patterns likely reflect adaptive phenotypic plasticity. In summary,
our study revealed pronounced plastic and genetic responses, which may
indicate high adaptive capacities in our study organism. Whether this may
help such species though to deal with current climate change needs further
investigation, as clinal patterns have typically evolved over long
periods.