Check this out: Epigenetics: How Evolution Is Evolving

I am not an expert on evolution. But I'd like to hear the comments/opinions of people here who are experts.
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I don't know much about epigenetics, but aren't prions usually quite limited in the number of alternative forms they can take? Like two? Of course there are probably many different types of prions so I suppose there is room for them to have some significant effect on the evolution of an organism, but I think we shouldn't be rewriting the books just yet.

Read an article not too long ago on epigenetics, and reading about the history of evolution right now - came across Lamarkian evo & was wondering this same thing. Hopefully someone in the field will stop in for a chat.

Bookmarked.

PsYcHoTiC_MaDmAn wrote:in specific examples of epigenetics. the one I came across involved the effects of starvation of one generation resulting in a reduction in life expectancy. this is Lamarckism in essence.

Uh, wouldn't Lamarckism rather be, for instance, the offspring of a trained sportsman being genetically sportive.

One must note that epigenetics can only act on pre-existing genomic material, so the acquisition of novel phenes depends on darwinian evolution, what epigenetics can do is alter pre-existing gene expression patterns and confer some degree of heritability in descendants.

The extant genome is a major constraining factor.

I've just been reading about the book Evolution in four dimensions by E. Jablonka and M. J. Lamb, the four dimensions being genetic, epigenetic, behavioural and symbolic. If you've read it, I'd be very interested in reading your thoughts (especially on the last two "dimensions", which seem more properly "Lamarckian", and on their place in discussing evolution).

Epigenetics is real, Lamarckism is not. Although epigenetics allows certain gene expressions to differ based on environmental conditions in the parental line, it cannot acquire or evolve any new gene expressions not already present. In other words, it doesn't 'evolve'. Only mutations in the actual genes can change the base code required for true evolution. Epigenetics is more like two identical radios tuned to different stations, and no amount of station swapping will make a better radio.

my_wan wrote:Epigenetics is real, Lamarckism is not. Although epigenetics allows certain gene expressions to differ based on environmental conditions in the parental line, it cannot acquire or evolve any new gene expressions not already present. In other words, it doesn't 'evolve'. Only mutations in the actual genes can change the base code required for true evolution. Epigenetics is more like two identical radios tuned to different stations, and no amount of station swapping will make a better radio.

No, but if their tuning buttons are stuck, one of the radios may be chucked out of the window for being a nuisance and the other given a chance to ... er ... produce the next generation of cute little radios?

I don't think anybody is suggesting that we bring back the (caricature of?) Lamarckism we read about in our textbooks. I find this quote from wikipedia sums up quite well the issue of neo-Lamarckism:

In addition to 'hard' or genetic inheritance, involving the duplication of genetic material and its segregation during meiosis, there are other hereditary elements that pass into the germ cells also. These are considered "Lamarckian" in the sense that they are responsive to environmental stimuli and can differentially affect gene expression adaptively, with phenotypic results that can persist for many generations in certain organisms. Although the reality of epigenetic inheritance is not doubted (as many experiments have validated it), its significance to the evolutionary process is uncertain. Most neo-Darwinians consider epigenetic inheritance mechanisms to be little more than a specialized form of phenotypic plasticity, with no potential to introduce evolutionary novelty into a species lineage.

katja z wrote:
I don't think anybody is suggesting that we bring back the (caricature of?) Lamarckism we read about in our textbooks. I find this quote from wikipedia sums up quite well the issue of neo-Lamarckism:

In addition to 'hard' or genetic inheritance, involving the duplication of genetic material and its segregation during meiosis, there are other hereditary elements that pass into the germ cells also. These are considered "Lamarckian" in the sense that they are responsive to environmental stimuli and can differentially affect gene expression adaptively, with phenotypic results that can persist for many generations in certain organisms. Although the reality of epigenetic inheritance is not doubted (as many experiments have validated it), its significance to the evolutionary process is uncertain. Most neo-Darwinians consider epigenetic inheritance mechanisms to be little more than a specialized form of phenotypic plasticity, with no potential to introduce evolutionary novelty into a species lineage.

It's not Lamarckian,or neo-Lamarckian. It's another level of control over gene expression that is heritable between cell generations (contentious as to the stability of its heritability over organismal generations), in much the same way miRNA, piRNA and long ncRNA also exhibit additional levels of control over gene expression. It has certainly evolved as a mechanism itself, but that does not in any way predicate Lamarckian evolution.

Genesforlife certainly put it right in that it may have evolved as another layer of phenotypic plasticity. The question I'd like to find an answer to is whether genomic imprinting predates more dynmaic epigenetic changes observed within the genome, or vice versa? Is it possible that epigentic changes were present at an early stage in eukaryotic evolution, but competition between the sexes created an evolutionary pressure that led to the adaptation of epigenetic mechanisms to differential (sex-specific) genomic imprinting?

I am not aware of any projects aimed at studying long term epigenetic influences on evolutionary changes within populations, though I imagine they are being carried out. Perhaps someone more familiar with advances in the field can provide a few cogent examples.

MedGen wrote:
It's not Lamarckian,or neo-Lamarckian. It's another level of control over gene expression that is heritable between cell generations (contentious as to the stability of its heritability over organismal generations)

Thanks for clarifying this!

I am not aware of any projects aimed at studying long term epigenetic influences on evolutionary changes within populations, though I imagine they are being carried out. Perhaps someone more familiar with advances in the field can provide a few cogent examples.

That would be very interesting, I was just going to ask how far down the line (how many generations) such effects could be noticed.

PsYcHoTiC_MaDmAn wrote:

MedGen wrote:

I am not aware of any projects aimed at studying long term epigenetic influences on evolutionary changes within populations, though I imagine they are being carried out. Perhaps someone more familiar with advances in the field can provide a few cogent examples.

I thought I'd put a link in with my comment on life expectancy. I hadn't so this was what I was referring to

http://www.bbc.co.uk/sn/tvradio/programmes/horizon/ghostgenes.shtml
http://www.nature.com/ejhg/journal/v14/n2/full/5201567a.html
http://www.time.com/time/health/article/0,8599,1951968,00.html

You also see the same effect with maternal diet, offspring birth weight and the incidence of type-2 diabetes mellitus, which was demonstrated by studying the Dutch winter famine following operation Market Garden in the Netherlands. I was more specifically referring to studies that studied the molecular basis (i.e. the actual epigenetics marks on chromatin and CpG islands) through multiple generations.

This is what I wrote a while ago in the now defunct RD Forum for the thread Lamarkian Evolution:

by Federico » Sat Dec 20, 2008 3:28 pm


Net Traveller wrote:
in a copy of new scientist magazine i read an artical where Richard Dawkins was quoted, the artical was called 'Strange Inheritance" and was written I think by Emma Young. The article talked about how some biologists now think Lamarck was write about certain things and that traits aquired in an individuals life time can be passed on to offspring without any change to genes taking place. it then goes on to quote a professor called Eva Jablonka to say that "It means the demise of the selfish gene theory". In that article Dawkins was then quoted to say that the selfish gene theory can still work, just with the word 'replicator replacing 'gene'.
I mention this because I found the article difficult to follow, particular the part where he was quoted, I mean, How would this idea "mean the demise of the selfish Gene"? I dont understand what the problem is? How seriously is this "new Lamarckism" being taken?

Federico wrote:
The way I understand it -- but I won't bet my bippy on it -- the whole RD theory of the selfish gene is based upon the classical Darwinian evolutionary process where genes are mutated in a time frame of thousand of years and according to a scheme which would be advantageous to the individual thus to the gene itself.
The recent discovery of new mechanisms of evolution where not the gene itself is mutated but the genomic apparatus controlling gene's expression is modified by the environment within a much shorter time frame, has given new credence to Lamarkism and the possible transmission within a generation of newly acquired adaptive characteristics.


A discovery made recently at the Université de Montréal by Dr. Stephen Michnick brings further proof for the existence of an additional mechanism for transmission of genetic information which is based on nuclear proteins and which can be influenced by the environment.

University Of Montreal Researcher Explores How Genes And Proteins Interact To Build Life's Dynamic Architecture

"We think of genes and proteins interact in the same manner as people process sentences," says Dr. Michnick. "Living cells do something similar with genes: proteins read DNA sequence from beginning to end and translate this information in turn into new proteins, which are essentially molecules that build the cells structure and control biochemical processes. But like language, there's much more to it than a simple grammatical problem; there are more abstract processes at the heart of reading genes that we need to understand."

"Dr. Michnick, who was recruited to the Université de Montréal from Harvard University, routinely collaborates with top scientists in his quest to know where life began. In a recent study published in the journal PLoS Biology, led by Harvard University's Fred Winston, the University of Toronto's Tim Hughes, Dr. Michnick and the Université de Montréal's Christian Landry helped identify genes that code for proteins that in turn control the reading of genes.

"The study provides insight into the fundamental mechanisms of epigenetic control - gene expression that are controlled by heritable but potentially reversible changes in DNA - which provides a new avenue towards understanding environmental effects on the human genome.
"Epigenetic control is needed to direct the development of an embryonic stem cell, for instance, into a brain as opposed to a kidney cell," Dr. Michnick says. "Control of genes is subject to both inherited and environmental factors, so that genes may be read differently and up to what a person eats or even what their grandmother ate."

Darwin himself did believe that traits from a mother, willfully novel in her, could be translated to offspring.
He was in his book'Descent" talking about female biological intellectual inferiority and he suggested this could possibly be fixed by a women studying/thinking real hard and then this be genetically, our word, put into female offspring.
So he did accept ACQUIRED traits being translated to offspring who otherwise would not have these traits.

I recently saw a NOVA episode on dogs in which they come close to LAM stuff. they talk about domestic dogs aquiring from parents traits etc.
Anyways i do see innate triggers in biology as the origin of changes. Just like a kid upon puberty changing in parts and details. Its innate within a biological equation to maintain life.

Robert Byers wrote:Darwin himself did believe that traits from a mother, willfully novel in her, could be translated to offspring.

[1]What the fuck is wilfully novel?
[2]In case you did not get the memo, epigenetics can only alter states of pre-existing genomic material. It can alter and modify phenes through altered gene expression, and these expression patterns can be inherited, that is it.

He was in his book'Descent" talking about female biological intellectual inferiority and he suggested this could possibly be fixed by a women studying/thinking real hard and then this be genetically, our word, put into female offspring.

[1] Do you have a citation for this?
[2] As has already been posted, epigenetics can only act upon pre-existing genetic material.

So he did accept ACQUIRED traits being translated to offspring who otherwise would not have these traits.

Two words - August Weismann, homework for you.

I recently saw a NOVA episode on dogs in which they come close to LAM stuff. they talk about domestic dogs aquiring from parents traits etc.

All genes are inherited from parents, and all inherited dominant traits are expressed. Standard heredity, Byers, standard heredity.

Anyways i do see innate triggers in biology as the origin of changes. Just like a kid upon puberty changing in parts and details. Its innate within a biological equation to maintain life.

do you realize that triggers are useless without a gun to fire?

GenesForLife wrote:

So he did accept ACQUIRED traits being translated to offspring who otherwise would not have these traits.

Two words - August Weismann, homework for you.

GFL, not that I'm quarelling with the homework, but Byers does seem to have got that bit right, sort of - Darwin did speak about variability "from use and disuse" at the end of the Origin. Of course, this doesn't mean what Byers thinks it means for ToE - and I think it is important to clarify in this kind of debate that Darwin, who had no way of knowing about genes, had some very mistaken ideas on the actual mechanism of heredity (I've just come across his concept of "gemmules" in Jablonka and Lamb's Evolution in Four Dimensions). In other words, the memo Byers doesn't appear to have got is that not everything Darwin ever said is held to be correct by contemporary biologists, and that just trotting out random quotes from his writings doesn't constitute an argument (except in a discussion on the history of evolutionary biology).

katja z wrote:

GenesForLife wrote:

So he did accept ACQUIRED traits being translated to offspring who otherwise would not have these traits.

Two words - August Weismann, homework for you.

GFL, not that I'm quarelling with the homework, but Byers does seem to have got that bit right, sort of - Darwin did speak about variability "from use and disuse" at the end of the Origin. Of course, this doesn't mean what Byers thinks it means for ToE - and I think it is important to clarify in this kind of debate that Darwin, who had no way of knowing about genes, had some very mistaken ideas on the actual mechanism of heredity (I've just come across his concept of "gemmules" in Jablonka and Lamb's Evolution in Four Dimensions). In other words, the memo Byers doesn't appear to have got is that not everything Darwin ever said is held to be correct by contemporary biologists, and that just trotting out random quotes from his writings doesn't constitute an argument (except in a discussion on the history of evolutionary biology).

Yup, I never said that Darwin did not claim anything of that sort, to be clear on this you may notice I was asking for a citation, leaving that possibility open. Also, I was pointing out to Byers that even if Darwin did assert as such, August Weismann demonstrated that Larmackism per se does not work, even if this was a bit cryptic.

GenesForLife wrote:
Yup, I never said that Darwin did not claim anything of that sort, to be clear on this you may notice I was asking for a citation, leaving that possibility open. Also, I was pointing out to Byers that even if Darwin did assert as such, August Weismann demonstrated that Larmackism per se does not work, even if this was a bit cryptic.

Absolutely, I just wanted to make things clearer, because it was a bit cryptic for a non-biologist, not to speak of someone so well versed in biology as our friend Byers

About the Prions (@Kytescall & @PsYcHoTiC_MaDmAn) ; The part about prions in the article was based mainly upon Lindquist et al. research on the inheritability of prions in yeast. It has been noted that Yeast and other kinds of fungi also have the "Prion proteins" which are those proteins which are affected by the prions. Prions are epigenetic factors as they manage to change the phenotype through the misfolding of the proteins, without changing the genetic code. Lindquist et al. argue that these misfoldings could be considered kind of like mutations that do not involve the genetic code, and that some misfoldings could actually be beneficial in some case (Just like mutations). The offspring would then have the proteins folded differently as well, and thus this would be passed on from mother to offspring. The whole prion deal is still not well understood; there is no general consensus about how the prion gets the prion proteins to misfold like them, and I believe there is still some controversy about Lindquist et al.'s interpretation.

Some links:
Prion research @ MIT
Lindquist's publications
Lecture on Prions by Lindquist

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Lamarck thought that the traits which the parents acquired during their lifetime would be passed onto their offspring. That is, someone who trained his running a lot would have better runners as children, who could then train more their running and have offspring which were even better. So, what the parents do is passed onto their offspring.

Epigenetics looks at all of the changes that affect the phenotype without touching the genotype. This includes the prions, like stated above, which affect the phenotype by changing the way the proteins are folded but do not touch the genotype at all. However, the most studied area of epigenetics is the expression of genes. Genes are activated and silenced during the development of the organism, and extrinsic factors play a role in how the genes are activated and silenced. The effects that the environment can have on the expression might be due to adaptation like Daphnia sp.'s morpholical plasticity and other organisms, or they may just be a by-product. (For example, it is known that frog eggs in higher temperature will usually hatch with a lower body mass, and I believe this is due to a biophysical/chemical constraint rather than due to adaptation. I'm not sure though).

For example, if Daphnia are exposed to their predator the midge larva during their development, the gene expression will change, and their morphology will be different. Their heads and tails will elongate, make it harder for the predator to ingest them. However; the Daphnia that are in this elongated state have less offspring. This is know as antagonistic pleiotropy - The activation of the gene which will increase fitness in one way (Reducing risk of death due to predation) but will reduce fitness in another way (reduced offspring).* Thus, the Daphnia have evolved this epigenetic mechanism - If there if the Daphnia senses the molecules of the predator in the water, its development will go in the pointy direction, reducing the risk of death.. If not, then the Daphnia's morphology will remain neutral and it will have more offspring. This is called "norm of reaction". That is, environmental cues affect the development of certain phenotypes.

This lecture from Yale talks about different reaction norms. The whole course is very interesting.





*If someone could tell me if I am correct in this, I would appreciate it. I know that antagonistic pleiotropy is when one gene affects more than one traits in the phenotype; some of them being helpful and the other being detrimental. However, I am not sure if this specific case would be considered a.p. because the reduced offspring is not necessarily coded by the gene but is rather a by-product of the use of energy or maybe space constraints. (Although, it is a direct effect of the gene in the sense that its activation is the cause).