Epigenetic mechanisms are central to gene regulation, phenotypic plasticity, development and the preservation of genome integrity. Epigenetic mechanisms are often held to make a minor contribution to evolutionary change because epigenetic states are typically erased and reset at every generation, and are therefore, not heritable.
First, some epigenetic states are transmitted intergenerationally and affect the phenotype of offspring.
econd, epigenetic variation enhances phenotypic plasticity and phenotypic variance and thus can modulate the effect of natural selection on sequence-based genetic variation.
Third, given that phenotypic plasticity is central to the adaptability of organisms, epigenetic mechanisms that generate plasticity and acclimation are important to consider in evolutionary theory.
Fourth, some genes are under selection to be ‘imprinted' identifying the sex of the parent from which they were derived, leading to parent-of-origin-dependent gene expression and effects.
DNA methylation and other chromatin modifications directly affect the rate of mutation in DNA. Hence epigenetic mechanisms directly affect genome evolution.
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