That’s negation in the “contradicting” sense of the term, rather than as in nullification or reversal. That being said, Jeffrey Tomkins’ headline today is “Plant Epigenome Research Negates Evolution,” which in theory could mean that epigenetics is acting to actively prevent the changes that evolution is creating. This is not, however, the case – at least not here.
Biological research involves a lot of “model organisms,” one of which is the thale cress, Arabidopsis thaliana. The paper that Tomkins is talking about today – Patterns of population epigenomic diversity (open access) – compares the patterns of DNA methylation of thale cress plants adapted to different environments, which they found to be much larger than they expected. DNA methylation involves the attachment of a methyl group to a base of DNA, which could be thought of as acting as a speed bump for transcription, slowing it down or stopping it entirely but in a way that can be undone if the group is removed. Eukaryotes like animals and plants seem to use every potential mechanism available to regulate gene expression, and this is no exception. And just as the sequence of As, Gs, Cs, and Ts can be determined and is called a genome, so too can the pattern of methylation within that genome be mapped – this is your “epigenome.” Continue reading