Thread: Evolution Gene

Has candidate evolution genes ever been identified or some indicative evidence been found? Such a gene could maybe be more susceptible to increased levels of various types of radiation or mutation-causing chemical levels, could maybe work towards a favoring of non life threatening mutations or maybe even, when turned on, provide for a Lamarckian type of evolution to occur? Is it possible that such a gene could be hiding in junk DNA?

Aren't all genes evolution genes?

You mean that all genes can undergo mutation? Sure, I agree, but I was thinking about a gene that might facilitate Lamarckian evolution when a group of organisms are subjected for extended periods to stimulae they are not adapted to. I mean like newly available niches after mass extinctions and all the changes to environment that caused them for instance. Basically a gene that would enhance a creature's adaptability. Such a gene, if possible, could surely have been selected for, once it emerged?

Plants can have rather different phenotypes dependent on the environment. That is with exactly the same genotype. The 'genes' can be used in a 'creative' manner sort of.

Lamarckian genes do not exist since no mutation can spread from the somatic cells to the germline.

Originally Posted by spuriousmonkey

Plants can have rather different phenotypes dependent on the environment. That is with exactly the same genotype. The 'genes' can be used in a 'creative' manner sort of.

Lamarckian genes do not exist since no mutation can spread from the somatic cells to the germline.

Though the Baldwin effect is very close to Lamarckian in some of its manifestations.

I agree, however, that there is unlikely to be any particular 'evolution' gene. Rather there are some genes that are very conservative in terms of their changes possibly because, developmentally, their actions occur very early on and therefore, if changed, simply result in spontaneous abortion. Other genes may not be so developmentally contrained. But this will probably just bring us back to discussion of Hox and Homœobox etc...

Plants can have rather different phenotypes dependent on the environment. That is with exactly the same genotype. The 'genes' can be used in a 'creative' manner sort of.

Cool. I'd imagine that similar effects can be noticed with animals? So then the way genes are expressed can be influenced directly by the environment. But the genes themselves remain unchanged. Might it be possible that variations of chemicals that can be associated with environment (and that are reflected in the bloodstream) might affect genes during gametogenesis by way of an evolution gene?

One problem I can think of is why such a gene would only come into play during a change in environment. Let’s say that an evolution gene was always turned on and organisms were able to, as a rule, adapt readily to any changes in environment. This is obviously not the case, but if an evolution gene was in fact possible and existed, why then would it be a bad thing for it to always be turned on? Can there be a disadvantage to being able to adapt at the drop of a hat?

Originally Posted by KALSTER

Cool. I'd imagine that similar effects can be noticed with animals? So then the way genes are expressed can be influenced directly by the environment. But the genes themselves remain unchanged.

This happens a lot actually.

Originally Posted by KALSTER

Might it be possible that variations of chemicals that can be associated with environment (and that are reflected in the bloodstream) might affect genes during gametogenesis by way of an evolution gene?

I really think you need to get away from the idea of an evolution gene. There's no evidence (that I am aware of) of directed chromosomal or homologous recombination events during meiosis. It's an intersting idea but one which would probably need the involvement of multiple genes. It's quite possible that environment will play a key role in phenotype during conception, embryogenesis, foetal development and beyond etc. but this is nothing novel.

Originally Posted by KALSTER

One problem I can think of is why such a gene would only come into play during a change in environment. Let’s say that an evolution gene was always turned on and organisms were able to, as a rule, adapt readily to any changes in environment. This is obviously not the case, but if an evolution gene was in fact possible and existed, why then would it be a bad thing for it to always be turned on? Can there be a disadvantage to being able to adapt at the drop of a hat?

But organisms can adapt rapidly to their environments. It just doesn't have a genetic basis. Rather it has a gene expression basis. If we were able to switch on more rapid gene mutation rates in some manner, it would probably be pretty disastrous for the organism in question. Mutations are chaotic, the vast majority of mutations are detrimental to the host. That our mutation rate is at its current level is as much a survival characteristic as any other.

We do have certain hypervariable regions of our genome, but this is a sort of controlled chaos system used for very specific tasks.

Originally Posted by KALSTER

Plants can have rather different phenotypes dependent on the environment. That is with exactly the same genotype. The 'genes' can be used in a 'creative' manner sort of.

Cool. I'd imagine that similar effects can be noticed with animals? So then the way genes are expressed can be influenced directly by the environment. But the genes themselves remain unchanged. Might it be possible that variations of chemicals that can be associated with environment (and that are reflected in the bloodstream) might affect genes during gametogenesis by way of an evolution gene?

One problem I can think of is why such a gene would only come into play during a change in environment. Let’s say that an evolution gene was always turned on and organisms were able to, as a rule, adapt readily to any changes in environment. This is obviously not the case, but if an evolution gene was in fact possible and existed, why then would it be a bad thing for it to always be turned on? Can there be a disadvantage to being able to adapt at the drop of a hat?

You're still thinking of a hypothetical (and probably non-existent 'evolutionary gene'), and building an entire superstructure of theory around it.

With regard to environmentl effects on animals, the most obvious example is poor nutrition in humans in developing areas, and the consequent height at adulthood.

If that sounds too commonplace, look up the Axolotl and its sensitivity to iodine in terms of changing from a neotenous adult to a fully metamorphosed adult.

Even if putative genes, more easily moulded by natural selection, were to exist, to have them 'turned on' at all times, even when not needed, would incur an energy/resource cost and would be selected against. A lot of such genes, therefore, only express themselves in stressful circumstances (large changes in the environment) when the reproductive process appear to get into a desperate-times-requuire-desperate-measures sort of state. Apropos, anthropological (sociological? demographic?) studies appear to show that young ladies in unstable family/life circumstances reach menarche earlier, possibly as a result of their reproductive systems deciding that life is too uncertain to take a chance on reaching full maturity - do it now! I wish I could find a reference, but perhaps one of you could.

You're still thinking of a hypothetical (and probably non-existent 'evolutionary gene'), and building an entire superstructure of theory around it.

Not building any theory. I'm simply placing it on the table so we can poke at it with a stick. :wink:

Even if putative genes, more easily moulded by natural selection, were to exist, to have them 'turned on' at all times, even when not needed, would incur an energy/resource cost and would be selected against.

Yeah, that looks like a good enough reason for it not to be permanently turned on.

There's no evidence (that I am aware of) of directed chromosomal or homologous recombination events during meiosis.

Have studies been conducted under adverse conditions or in the presence of varying levels of chemicals one might expect to be affected by specific environmental dynamics?

It's quite possible that environment will play a key role in phenotype during conception, embryogenesis, foetal development and beyond etc. but this is nothing novel.

Whatever works I guess. How does phenotypic variation (by way of induced cell morphogenesis perhaps?) then translate into genotypic variation of isolated or niche exploring populations, eventually creating new species?

If we were able to switch on more rapid gene mutation rates in some manner, it would probably be pretty disastrous for the organism in question. Mutations are chaotic, the vast majority of mutations are detrimental to the host. That our mutation rate is at its current level is as much a survival characteristic as any other.

I understand and agree with this. That is why I was suggesting that if an "evolution gene/s" existed, that it would only affect certain areas that are less likely to kill the mutant or make it sterile.

How is the "junk" label assigned to a DNA section?

Originally Posted by KALSTER

There's no evidence (that I am aware of) of directed chromosomal or homologous recombination events during meiosis.

Have studies been conducted under adverse conditions or in the presence of varying levels of chemicals one might expect to be affected by specific environmental dynamics?

That's a very, very vague question. Firstly you need to define some conditions, then you need to check pubmed or google scholar for papers on meiosis under those conditions.

Originally Posted by KALSTER

It's quite possible that environment will play a key role in phenotype during conception, embryogenesis, foetal development and beyond etc. but this is nothing novel.

Whatever works I guess. How does phenotypic variation (by way of induced cell morphogenesis perhaps?) then translate into genotypic variation of isolated or niche exploring populations, eventually creating new species?

Natural selection eliminates phenotypes unfit for a given environment, thus eliminating the causative genotypes.

Originally Posted by KALSTER

If we were able to switch on more rapid gene mutation rates in some manner, it would probably be pretty disastrous for the organism in question. Mutations are chaotic, the vast majority of mutations are detrimental to the host. That our mutation rate is at its current level is as much a survival characteristic as any other.

I understand and agree with this. That is why I was suggesting that if an "evolution gene/s" existed, that it would only affect certain areas that are less likely to kill the mutant or make it sterile.

How is the "junk" label assigned to a DNA section?

Typically I think this is the generic label for DNA which is not within the sequence of a gene, be it an expressed part (exon) or non-expressed part (intron). "Junk DNA" is a term I would hesitate to ever use as it suggests a lack of function and non-expressed DNA is known to have a number of functions.

I found THIS article at PNAS. Not sure you will be able to view the entire article (I am in a developing country :wink: )

Abstract:

"Concomitant with the evolution of biological diversity must have been the evolution of mechanisms that facilitate evolution, because of the essentially infinite complexity of protein sequence space. We describe how evolvability can be an object of Darwinian selection, emphasizing the collective nature of the process. We quantify our theory with computer simulations of protein evolution. These simulations demonstrate that rapid or dramatic environmental change leads to selection for greater evolvability. The selective pressure for large-scale genetic moves such as DNA exchange becomes increasingly strong as the environmental conditions become more uncertain. Our results demonstrate that evolvability is a selectable trait and allow for the explanation of a large body of experimental results."

Has this avenue been explored by others? It seems to explain a lot of things I have been wondering about. What do you guys think?

http://www.pubmedcentral.nih.gov/art...gi?artid=94481

Well there used to be a lot of talk about directed mutation in bacteria, since under starvation conditions they seemed to evolve quite rapidly to use new sources of nutrition. "Directed" is misleading though, since it suggests thought and intention. Rather just some organisms have ways to promote evolution, by promoting mutation under certain conditions. In that way I guess there could be "evolution genes". This hypermutation is seen in mammals also, where B cells undergo processes of hypermutation to create diversity.

Somewhat related to the question at hand:

http://www.ncbi.nlm.nih.gov/books/bv...o.section.5122

Kalster I think you might be interested in reading Nature via Nurture, which explores the influence the environment has on the expression of genes. It turns the old Nature versus Nurture arguments on their head and focuses on how intimately related the two aspects of life are.

Nature Via Nurture: Genes, Experience, and What Makes Us Human, Matt Ridley.

I think it may have been updated as The Agile Gene.

When I see the word "evolution genes" I think of transposons, which are DNA sequences that are able to "jump", or transpose, from one location in the genome to another. Transposons cause various types of spontaneous mutations by bringing along its adjacent genes during its tranpositions, insertion into the introns of a gene (which may result in the alteration of splice sites and disrupt control elements within the target gene), and may also cause frameshift mutations.

In fact transposons are a key component of the hypermutation process in the immune system response to produce antibody. I'm thinking that environmental stimuli may bring about the activation or repression of the expression of these transposon genes to alter the level of mutation.

So IMO transposons may be a possible candidate for "evolution genes".

Evolution genes, if they exist, would likely be quite favourable. Is it then reasonable to assume that evolution might have accelerated more and more during the appearance of these evolution genes? I guess it depends upon how they work with other genes as well.

If we find these genes we might track back to their appearance. After that we can check other fields of research if the evidence might point towards an increasingly accelerating evolution due to these genes (fossil record perhaps. It's uncertain what we should look for though).

Or we might try and locate where these genes began by trying to determine where the acceleration can be clearly seen (assuming there is an acceleration) and then try to find these evolution genes.

It might also be a possibility that we contain a number of genes which are "stored" and switched off which might start to function when the time for it comes (when the enviroment changes), thus causing an accelerated evolution to adapt to the new enviroment which triggered these genes. If I'm not mistaken, humans have genes for gills, right?

I'm not sure what to think at this time... And I'm not really that knowledgable within the subject.

Originally Posted by arkofnoah

In fact transposons are a key component of the hypermutation process in the immune system response to produce antibody.

Well it certainly looks like a spookily similar system but I'm not sure that it's clear that transposons are the origin of the B cell hypermutation system. It could equally be an example of a convergent evolution. Perhaps we did nab the system conventional transposons.

Originally Posted by arkofnoah

I'm thinking that environmental stimuli may bring about the activation or repression of the expression of these transposon genes to alter the level of mutation.

So IMO transposons may be a possible candidate for "evolution genes".

Only if they possess such regulatory elements in themselves. They certainly provide a vast bank of ready-made gene bits for the modification of existing genes.

Is it just me, or does anyone else think that the OP is just over thinking meiosis?

Originally Posted by Cr4sh

Is it just me, or does anyone else think that the OP is just over thinking meiosis?

Well yeah, all of this would happen during meiosis. That is, mutations are both accelerated and directed or kept in check so neutral mutations (which could play a role in mutations later on, either good or bad) or mutations that do not affect the robustness of an organism too much over he whole population in the event of accelerated mutation/evolution, basically a gene or collection of genes that controls the evolvability of an organism. This gene/s would then be turned on by the environment where the meiosis is taking place in, which would in turn be affected by the enironment of the organism. Anyway, this is basically what I was thinking about and what was sort of tentatively confirmed by the link I found. I am satisfied.