Epigenetic mutations can both help and hinder adaptive evolution.

Area of Science:

• Evolutionary biology
• Genetics
• Epigenetics

Background:

• Understanding adaptation requires integrating epigenetic variation.
• Existing models lack the inclusion of de novo genetic change alongside epigenetic mutations.
• The interplay between epigenetic changes and genetic mutations in evolution is not fully understood.

Purpose of the Study:

• To model the effects of epigenetic mutations on adaptive walks.
• To investigate how epigenetic mutations influence the dynamics and outcomes of adaptation when de novo genetic change is also considered.
• To explore the conditions under which epigenetic mutations facilitate or impede evolutionary adaptation.

Main Methods:

• Utilized an individual-based model for an asexual population.
• Simulated adaptive walks, a process of sequential beneficial mutations towards a fitness optimum.
• Incorporated mutational effects drawn from Fisher's geometric model, considering both epigenetic and genetic changes.

Main Results:

• Epigenetic mutations can accelerate adaptation and lead to higher population fitness in some scenarios.
• Conversely, epigenetic mutations can also decelerate adaptation and result in lower population fitness.
• The influence of epigenetic mutations is critically dependent on their stability and fitness effects relative to genetic mutations.

Conclusions:

• Epigenetic mutations exhibit a complex relationship with natural selection.
• Small-effect epigenetic mutations tend to speed up adaptation.
• Epigenetic mutations with fitness effects similar to genetic mutations can slow down adaptation, underscoring the need for empirical data.