Transcriptomic responses to within- and intergenerational environmental warming in a cold-adapted salmonid

Cold-adapted species are particularly threatened by climate change as rates of environmental warming outpace the ability of many populations to adapt. Recent evidence suggests that intergenerational thermal plasticity may play a role in the response of cold-adapted organisms to long-term changes in temperature. Using RNA sequencing, we explored differential gene expression of lake trout (Salvelinus namaycush), a cold-adapted species, to examine the molecular processes that respond to elevated temperatures under conditions of within-generation (offspring) and intergenerational (parental) warm acclimation. We hypothesized that genes associated with metabolism, growth and thermal stress/tolerance would be differentially expressed in juvenile lake trout offspring depending on their own acclimation temperature and that of their parents. While parental warm acclimation did have an intergenerational effect on gene expression in their offspring, within-generation (offspring) warm acclimation had a greater effect on the number of differentially expressed genes. Differentially expressed genes enriched pathways for thermal stress, signaling processes, immune function, and transcription regulation and depended on the acclimation temperature of the offspring in isolation or in combination with parental warm acclimation. Despite evidence of intergenerational effects on gene expression in lake trout in response to elevated temperatures, the effect is unlikely to significantly increase populations' ability to cope with increasing environmental temperatures associated with climate change.