Comments on: Epigenetics again: will it cause a revolution in evolution?

By: Tinkering around is the best way to do research | Small Pond Science

Tinkering around is the best way to do research | Small Pond Science — Wed, 20 Mar 2013 12:32:10 +0000

[...] The one thing that students seem to learn in school about evolution is that Lamarck was wrong, and this lesson comes with a certain example involving a giraffe. It’s taken us a couple centuries to figure out that, to a certain extent, Lamarck was quite right about the inheritance of acquired characteristics after all. He just didn’t know the mechanism was epigenetic, just as Darwin wasn’t aware of the particulate inheritance mechanisms described by Mendel. Jerry Coyne addressed this a score of moons ago. [...]

By: Science-Based Medicine » Epigenetics: It doesn’t mean what quacks think it means

Mon, 04 Feb 2013 04:52:51 +0000

[...] (More on that later.) It’s an argument that Jerry Coyne has refuted well on more than one occasion. In [...]

By: Environment And Diet Leave Their Prints On The Heart « Health and Medical News and Resources

Wed, 30 Nov 2011 15:21:43 +0000

[...] Epigenetics again: will it cause a revolution in evolution? (whyevolutionistrue.wordpress.com) [...]

By: gillt

gillt — Thu, 29 Sep 2011 22:41:42 +0000

I’m not sure. Any DNA binding protein can alter histone binding and ultimately chromatin structure, right, so methylation specific binding proteins would fall under that rubric.

Also, I would reverse the cause and affect of the last clause: tight binding reduces transcription…we think.

By: Torbjorn Larsson, OM

Torbjorn Larsson, OM — Wed, 28 Sep 2011 16:47:11 +0000

My question was if histones can preserve methylation (or perhaps prevents it), as AFAIK it binds tightly on places were there is little transcription.

By: Dominic

Dominic — Wed, 28 Sep 2011 07:15:55 +0000

Because the grass is never that high!

By: gillt

gillt — Tue, 27 Sep 2011 21:17:24 +0000

They don’t go away because CpGs are nucleotides and their location in the genome is conserved across lineages. The question I think being asked is whether methylation (which effects gene expression) of CpGs is selected for.

And even then conserved methylation patterns are not themselves evidence of selection. This is because a CpG dinucleotide undergoes slow deamination if unmethylated and rapidly deaminates if methylated. This leads to stable CpG concentrations across related genomes.

To suggest selection you would have to show evidence of an islands increase or decrease GC content…a destablilizing event inferring either loss or gain of methylation. For that you need at least two points of comparison, say human and chimp.

This has been done.

Primate CpG islands are maintained by heterogeneous evolutionary regimes involving minimal selection.
Cell, 2011

By: Torbjorn Larsson, OM

Torbjorn Larsson, OM — Tue, 27 Sep 2011 19:14:43 +0000

I would look at it funny, considering that they ought to go away, see above.

Are we sure they aren’t locked in, say by histones for non-coding DNA?

By: Dominic

Dominic — Tue, 27 Sep 2011 19:06:03 +0000

I would say sexual selection is more likely…?

By: Dominic

Dominic — Tue, 27 Sep 2011 19:04:14 +0000

With such plasticity species would not be stable entities would they, as every individual would vary more easily so the only brake on evolution would be the increased incompatibility of individuals…?