DNA Methylation, Speciation and Domestication

More than 150 years after Mendel published his observations on the fundamental laws of inheritance and nearly 65 years after Avery provided unambiguous evidence that the hereditary material is DNA, unraveling the molecular basis underlying phenotypic plasticity and diversity is still a hot topic in genetics. Natural selection counteracts DNA sequence variation, yet losing genetic variation renders populations more vulnerable to changes in environmental conditions. This apparent contradiction can be resolved if adaptation is primarily dependent on altered gene regulation rather than on altered protein structures. Epigenetic modifications, which can effectively be maintained during cell division even across several generations, but at the same time are generally transient and as such, can flexibly be rearranged upon, e.g. environmental stimuli, offer an ideal solution to this inherent problem. In concert with these theoretical considerations, an increasing body of evidence demonstrates that evolutionary processes go hand in hand with shifts in epigenetic patterns, at least with regard to DNA methylation marks.