Recent studies have revealed that epigenetic variation in plant populations exceeds genetic diversity and that it is influenced by the environment. Nevertheless, epigenetic differences are not entirely independent of shared ancestry. Epigenetic modifications have gained increasing attention, because one can now study their patterns across the entire genome and in many different individuals. Not only do epigenetic phenomena modulate the activity of the genome in response to environmental stimuli, but they also constitute a potential source of natural variation. Understanding the emergence and heritability of epigenetic variants is critical for understanding how they might become subject to natural selection and thus affect genetic diversity. Here we review progress in characterizing natural epigenetic variants in model and nonmodel plant species and how this work is helping to delineate the role of epigenetic changes in evolution.
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