Epigenetics and Adaptation

Abstract

Epigenetic marks, such as DNA methylation, histone modifications, and non-coding RNAs, are molecules that regulate gene activity and can be passed on between cell divisions. By modulating gene expression and the physical structure of DNA, epigenetic marks can influence the phenotype of an organism and potentially of its offspring (if the marks are transmitted to the next generation). Thus, epigenetic marks have the potential to influence the evolutionary dynamics of natural populations. However, we are just starting to understand how and to what extent epigenetic marks affect evolutionary processes, including adaptation. In this chapter, we discuss the known drivers of variation in epigenetic marks among individuals and populations, touching on their genetic basis, the influence of the environment, and stochastic changes in epigenetic states. We then discuss the consequences of epigenetic marks on evolutionary dynamics, concerning different mechanisms of origination (i.e., genetic, or environmental) and degrees of transmission between generations. Depending on the characteristics of an epigenetic mark, it could aid survival in new habitats, promote genetic differentiation, or inhibit local adaptation. We highlight how epigenetic marks that do not affect phenotype can influence evolution by acting as mutagens and suppressors of transposable element proliferation. Lastly, we outline the current state of the field in natural population epigenetics. Resolving the gaps in the knowledge on the drivers of epigenetic variation and to which extent epigenetic marks are transmitted between generations will be key to resolving the debate about the importance of epigenetic mechanisms to adaptation.