Wounded King

Do epigenetic factors such as DNA methylation, histone methylation and histone remodelling provide a mechanism for the inheritance of acquired characteristics? How relevant may this process be to evolution?

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Itzpapalotl

Here is a link to: The marks, mechanisms and memory of epigenetic states in mammals (PDF) which says:

"The epigenetic inheritance we have described here is not Lamarckian, since it is due to the random failure to completely erase marks at certain alleles during development."

Epigenetic inheritance is an interesting phenomenon but does not seem to be able to mediate the sort of genetic change that is required for Lamarckian inheritance.

Wounded King

Perhaps I was being misleading when I headed this thread "Neo-Lamarckism". Obviously these epigenetic factors do not allow for something like longer necks to develop in giraffes, the classic Lamarckian scenario, but they do provide a mechanism for an acquired heritable effect.

The fact that the occurrence of these errors in epigenetic state maintenance occur randomly only means that they are not directed in the way Lamarck suggested, they would still provide a trait for natural selection to work upon.

So the effect is certainly not truly Lamarckian but is it the basis for a widening of the scope of evolutionary study? Quite how this might be done is not actually apparent to me as the stability of epigenetic states isnt well quantified, although in Paramecium it has been shown to be maintained for around a hundred generations through asexual reproduction. For a reference see the review mentioned above by itzapalotl, if any excepth me and thee are reading this of course itz.

RufusAtticus

At the very base of it, all mutations are acquired characteristics that are inherited.

Wounded King

Good point, well made. :notworthy

I no longer wish to associate my enquiries in any way with the concept of Lamarckian evolution.

That out of the way, would any like to address the issue of the scope of evolutionary study, is it too narrowly focussed on the AGTC of it all? How much of a seperate issue are epigenetic factors then? After all the CpG island targets for methyltransferases are part of the genome.

pz

Yes. We're at the point where we've developed a really good hammer in the molecular genetics toolbox, and so everything is looking like a nail.If you ask me, all the interesting stuff in genetics is in epistasis/developmental genetics/evo-devo. It has not been at all well incorporated into our understanding of evolution, yet.

scigirl

Well - the primary DNA sequence plays a role in where the methylations occur, so I'd say yes.

You mutate the DNA such that it gets more (or less) methylated, changing the amount of gene expression in that area, changing the phenotype that can be selected on.

scigirl

Wounded King

My point was that, while there are certain sequences particularly prone or resistant to methylatyation, this is not the be all and end all of methylation or histone architecture etc.. Therefore epigenetic factors may provide a mechanism independent from the primary sequence.