Abstract
Despite widespread taxonomic representation, the function of gene body methylation remains uncertain. One hypothesis is that GBM mediates phenotypic plasticity. To investigate this hypothesis, we performed whole-genome methylation and transcriptomic assays on reciprocally transplanted colony fragments of the reef-building coral Acropora millepora. We found that variation in gene body methylation (GBM) predicted coral fitness following transplantation. Specifically, for transplanted corals, similarity in GBM patterns to native corals positively correlated with growth rate, as well as carbohydrate, protein, lipid and endosymbiont content. Differences in GBM between populations also correlated with differences in transcription, with stronger GBM associated with elevated transcription. Our results further confirm GBM as a signature of stably active transcription and indicate that GBM tracks physiologically important genome-environment interactions.