Data from: DNA methylation of two heat-stress genes in redband trout from contrasting thermal environments

Epigenetic variation is a potential pathway for rapid response to environmental change and may influence local adaptation at the population level through population by environment interactions. Here, we focus on the most well-understood mechanism of epigenetic variation, DNA-methylation. Previous lab studies have shown consistent ecotypic variation in DNA-methylation, but few have attempted to quantify epigenetic variation in natural populations. We developed a study to compare levels of DNA-methylation in two heat-stress related genes in redband trout (Oncorhynchus mykiss gairdneri) from contrasting environments. We sampled trout populations from cold montane and warm desert streams at repeated intervals, collecting tissue samples that were used for epigenetic analysis and levels of DNA-methylation (percent methylation) were quantified using targeted bisulfite sequencing. There were no differences among fish from contrasting ecotypes in methylation at heat shock protein 70 (HSP70) or heat shock protein 47 (HSP47), indicating that seasonal changes in DNA methylation may occur at finer spatial scales than at the level of ecotype. However, there was significant variation in DNA methylation level between montane populations at heat shock protein 47. These findings suggest that DNA methylation is unlikely to act as a source of plastic adaptive phenotypic variation in natural redband trout populations and therefore may not contribute greatly to thermal adaptation in coldwater fishes. Further research is needed to better inform whether and when DNA methylation might act as a of adaptive phenotypic variation, and more specifically, how population-level adaptation may influence epigenetic change in wild populations.