Data from: Gene expression under thermal stress varies across a geographic range expansion front

Many ectothermic species are currently expanding their distributions
polewards due to anthropogenic global warming. Molecular genetic
mechanisms facilitating range expansion under these conditions are largely
unknown, but understanding these could help mitigate expanding pests and
disease vectors, or help explain why some species fail to track changing
climates. Here, using RNA-seq data, we examine genome-wide changes in gene
expression under heat and cold stress in the range-expanding damselfly
Ischnura elegans in northern Europe. We find that both the number of genes
involved and levels of gene expression under heat stress have become
attenuated during the expansion, consistent with a previously-reported
release from selection on heat tolerances as species move polewards. Genes
upregulated under cold stress differed between core and edge populations,
corroborating previously-reported rapid adaptation to cooler climates at
the expansion front. Expression of sixty-nine genes exhibited a region x
treatment effect; these were primarily upregulated in response to heat
stress in core populations but in response to cold stress at the range
edge, suggesting that some cellular responses originally adapted to heat
stress may switch to cold stress functionality upon encountering novel
thermal selection regimes during range expansion. Transcriptional
responses to thermal stress involving heat shock and neural function genes
were largely geographically conserved, while retrotransposon, regulatory,
muscle function and defence gene expression patterns were more variable.
Flexible mechanisms of cold stress response and the ability of some genes
to shift their function between heat and cold stress might be key
mechanisms facilitating rapid poleward expansion in insects.