From Jef Akst at The Scientist:
While animal cells undergo two rounds of reprogramming during reproduction to wipe clear most of the methyl marks that decorate their DNA and histones, plants leave their epigenomes largely intact from one generation to the next. In plants, this results in epialleles—stably inherited alleles encoded by methylation, rather than by gene sequence—that control subtle phenotypes, such as timing of flowering or fruit ripening.
Most of the differences [between individuals] that we see are caused by genetic variation,” says Colot. “But it’s not all caused by genetic variation. What would be caused by this epigenetic variation could be as important.”
Whether these epialleles can be adaptively altered by the environment remains a matter of debate, and most researchers say there is no convincing evidence for any form of such “Lamarckian” evolution. But there are hints that acquired changes in methylation patterns can impact future generations, and at the very least, errors in transcribing the methylome provide an additional source of new variation, akin to genetic mutation, as mistakes are stably inherited.
“There’s a lot more change possible epigenetically, and in some cases only possible epigenetically,” says Martienssen. “And selection just acts on that in the same way that selection would act on a genetic change.” More.
What is the difference between epigenetics and “Lamarckian” evolution that requires researchers to denounce it even while talking about what sounds an awful lot like it? Also, what does “selection” mean in the last sentence?: “And selection just acts on that in the same way that selection would act on a genetic change.” Some live and breed; others die and don’t?
Why is it necessary for these people to keep stating the obvious, unless they hope that we will all “get” some less obvious message?
See also: A new principle for epigenetic changes?
Epigenetic change: Lamarck, wake up, you’re wanted in the conference room!
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