The effect of experimental lead pollution on DNA methylation in a wild bird population

Anthropogenic pollution is known to negatively influence an organism’s physiology, behavior and fitness. Epigenetic regulation, such as DNA methylation, has been hypothesized as one mechanism to mediate such effects, yet studies in wild species are lacking. We first investigated the effects of early-life exposure to the heavy metal lead (Pb) on DNA methylation levels in a wild population of great tits ( Parus major ), by experimentally exposing nestlings to lead at environmentally relevant levels. Secondly, we studied the effects of heavy metal exposure in a population close to a copper smelter, where birds suffer from pollution-related decrease in food quality. For both comparisons, the analysis of about million CpGs covering most of the annotated genes, revealed that regions enriched for developmental processes showed pollution-related changes in DNA methylation, but the results were not consistent with binomial and beta binomial regression. Our study indicates that post-natal anthropogenic heavy metal exposure can affect methylation levels of development related genes in a wild bird population.