An organism's epigenome refers to markers that control how genes are expressed, without altering the underlying DNA sequences. When epi genetic landscapes are heritable, the parental environment could possibly influence the phenotype of progeny. Evidence of this transgenerational epigenetic inheritance in aquatic invertebrates is growing, and may be a mechanism linking parental exposures to offspring performance.
A major question, however, is how the underlying genome mediates epigenetic plasticity. For instance, DNA methylation changes in a stress-response gene may be universal in a group of taxa. Alternatively, changes could be highly specific to a locally adapted population, therefore making species-wide predictions difficult. It is important to know whether DNA methylation patterns are consistent across genetically-distinct families and populations. This is particularly pertinent for studies attempting to link epigenetic modifications to intergenerational plasticity, and in species with high genetic variability, such as oysters.
To assess the influence of genotype on DNA methylation patterns in the Olympia oyster (Ostrea lurida ), we raised individuals from two distinct populations in common conditions, and assessed both relatedness and methylation patterns using 2b-RAD and MBD-seq, respectively. We found distinct patterns in DNA methylation across po pulations and were able to associate DNA methylation with phenotype. Taken together, this study highlights the importance of considering DNA methylation in pursuing targeted phenotypes.