Epigenetic mutations can both help and hinder adaptive evolution

Abstract

Epigenetic variation is being integrated into our understanding of adaptation, yet we lack models on how epigenetic mutations affect evolution that includes de novo genetic change. We model the effects of epigenetic mutations on the dynamics and endpoints of adaptive walks-a process where a series of beneficial mutations move a population towards a fitness optimum. We use an individual-based model of an asexual population, where mutational effects are drawn from Fisher's geometric model. We find cases where epigenetic mutations speed adaptation or result in populations with higher fitness. However, we also find cases where they slow adaptation or result in populations with lower fitness. The effect of epigenetic mutations on adaptive walks depends crucially on their stability and fitness effects relative to genetic mutations, with small-effect epigenetic mutations generally speeding adaptation, and epigenetic mutations with the same fitness effects as genetic mutations slowing adaptation. Our work reveals a complex relationship between epigenetic mutations and natural selection and highlights the need for empirical data.

Evolutionary consequences of multidriver environmental change in an aquatic primary producer

“…This may be followed by compensatory mutations that increase fitness by reversing the effect of the initial mutation on traits where change was not adaptive (46)(47)(48). Second, heritable epigenetic mutations or transgenerational plasticity can contribute to early adaptation (7) but eventually be replaced by genetic mutations (49)(50)(51)(52). Understanding how trait reversion is linked to adaptation presents an opportunity to improve our predictions of functional trait values in primary producers in aquatic environments.…”

Rapid adaptive responses to climate change in corals

“…Throughout this paper we have largely discussed TGP in relation to its potential to influence offspring phenotype in an adaptive capacity. However, TGP can also be maladaptive 107,108 . This increases the need to understand TGP in response to climate change for conservation and management, since it could potentially constrain evolutionary processes 109 and hinder future species persistence.…”

Emerging Opportunities for Landscape Ecological Modelling

“…We also note that there are opportunities for novel work that takes a landscape perspective for major emerging themes in evolutionary biology. As two examples, we could begin to address questions related to the role of epigenetics in conferring adaptation across spatially heterogeneous landscapes by extending recent models that have focused on single populations [249,250]. We could also ask how landscape properties influence the role of sexual selection in driving trait evolution and how this evolution then shapes the dynamics of species ranges by extending individual-based models from evolutionary biology [251,252], or how different landscape structures may drive the evolution of different mating systems, again by exploiting the new and flexible IBMs [251,253] that are now being developed in the evolutionary field.…”