From epigenotype to new genotypes: Relevance of epigenetic mechanisms in the emergence of genomic evolutionary novelty.

A fundamental question in evolutionary biology is how heritable variability originates. In Darwinian evolution a central focus was placed on the thinking that random variations are the material basis for the action of natural selection. Although randomness in Darwinian evolution can be interpreted from different angles, here I will focus on the assumption of equiprobability of mutations. I have reviewed the literature regarding epigenetic mechanisms causing biased genetic variability. Although it is interesting to find correlations between somatic epigenetic marks and evolution, causation between epigenetic changes and genomic evolutionary novelties can only be established when the epigenetic changes are interrogated in the germ line. Epigenetic changes are reported to influence the emergence of single nucleotide polymorphisms and copy number variations. On the other hand, epigenetic changes are known to be influenced by environmental exposures. This dual ability of epigenetic changes could mean that germ line epigenetically influenced mutations could have an important role in the emergence of genomic evolutionary novelties. The emergent knowledge on the relation of epigenetic changes and mutations will help to understand an underappreciated role of the environment in speciation and genomic divergence: that of influencer of genomic changes.