Evolution Genes: The Story Continues

If the recA gene is an evolution gene, we would predict that its removal would somehow negatively impact the ability to evolve. So let's see what happens when RecA function is removed by mutation.

This entry was posted on Friday, August 17th, 2007 at 9:59 am and is filed under Evolution, Intelligent Design. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

34 Responses to “Evolution Genes: The Story Continues”

Doug Says:
August 17th, 2007 at 12:17 pm
Hi Mike,
Thanks for the update to the evolution gene/RecA story.

RecA is practically universal, highly conserved and deletion of it does not seem to hinder the bacteria's vitality.
What is its secondary function that allows it to be conserved?
Or is RecA dependent recombination its secondary function?

Comment by Doug — August 17, 2007 @ 12:17 pm

hrun Says:
August 17th, 2007 at 2:09 pm
RecA is practically universal, highly conserved and deletion of it does not seem to hinder the bacteria's vitality.

This is of course utterly incorrect. The deletion of RecA does not hinder the bacterias vitality in the absence of DNA damage causing agents. RecA is, for example, required to repair DNA damage caused by UV light, which, as should be known in the age of skin cancer, is ubiquitous in areas that are exposed to sunlight (i.e. outside of the laboratory).

So, the deletion of RecA certainly DOES hinder the bacterias vitality.

Quite possibly, that would also be a better explanation for the absence of RecA in some endosymbionts– namely their reduced exposure to DNA damage.

Comment by hrun — August 17, 2007 @ 2:09 pm

Bradford Says:
August 17th, 2007 at 2:17 pm
hrun:

This is of course utterly incorrect. The deletion of RecA does not hinder the bacterias vitality in the absence of DNA damage causing agents. RecA is, for example, required to repair DNA damage caused for example by UV light, which, as should be known in the age of skin cancer, is ubiquitous in areas that are exposed to sunlight (i.e. outside of the laboratory).

You raise a good point hrun. It illustrates why I believe DNA repair mechanisms are the ultimate front loading systems. Hard to imagine life without them.

Comment by Bradford — August 17, 2007 @ 2:17 pm

hrun Says:
August 17th, 2007 at 2:22 pm
You raise a good point hrun. It illustrates why I believe DNA repair mechanisms are the ultimate front loading systems. Hard to imagine life without them.

Again, this seems to be quite sloppy thinking. Just because the absence of RecA in the presence of UV light hinders/alters the bacterias vitality, this does not mean that the absence of RecA abolishes the bacterias vitality (i.e. is lethal).

As a side: I have no idea why you would call this a 'front loading system' if you can't imagine life without it. Wouldn't that rather qualify as some sort of 'IC system' depending on what the current definition of IC is.

Comment by hrun — August 17, 2007 @ 2:22 pm

Bradford Says:
August 17th, 2007 at 2:33 pm
hrun:

Again, this seems to be quite sloppy thinking. Just because the absence of RecA in the presence of UV light hinders/alters the bacterias vitality, this does not mean that the absence of RecA abolishes the bacterias vitality (i.e. is lethal).

Read carefully. My reference was to DNA repair mechanisms, not simply RecA.

As a side: I have no idea why you would call this a 'front loading system' if you can't imagine life without it. Wouldn't that rather qualify as some sort of 'IC system' depending on what the current definition of IC is.

DNA repair does involve multi-components of course but there is more to it than that. DNA repair ensures genomic integrity and therefore the viability of any evolutionary process.

Comment by Bradford — August 17, 2007 @ 2:33 pm

hrun Says:
August 17th, 2007 at 2:37 pm
Read carefully. My reference was to DNA repair mechanisms, not simply RecA.

It remains the same argument: while absence of DNA repair may be a (significant) disadvantage in the struggle for survival, it does not necessarily mean that it is not possible (merely hard to imagine by some).

Comment by hrun — August 17, 2007 @ 2:37 pm

Doug Says:
August 17th, 2007 at 2:41 pm
This is of course utterly incorrect.

This is melodramatic.

The deletion of RecA does not hinder the bacterias vitality in the absence of DNA damage causing agents.

I already understood this when I made my comment. The point was to ask the secondary function of the gene, allowing it to be conserved.

Comment by Doug — August 17, 2007 @ 2:41 pm

Doug Says:
August 17th, 2007 at 2:44 pm
Again, this seems to be quite sloppy thinking. Just because the absence of RecA in the presence of UV light hinders/alters the bacterias vitality, this does not mean that the absence of RecA abolishes the bacterias vitality (i.e. is lethal).

Wasn't this my point that you flipped out over?

Comment by Doug — August 17, 2007 @ 2:44 pm

hrun Says:
August 17th, 2007 at 2:44 pm
I already understood this when I made my comment. The point was to ask the secondary function of the gene, allowing it to be conserved.

Why do you need a secondary function to conserve the gene if the primary function does the trick already?

Comment by hrun — August 17, 2007 @ 2:44 pm

Bradford Says:
August 17th, 2007 at 2:49 pm
It remains the same argument: while absence of DNA repair may be a (significant) disadvantage in the struggle for survival, it does not necessarily mean that it is not possible (merely hard to imagine by some).

The quality of your imagination should have nothing to do with an empirical matter. The nature of an evolutionary process is altogether different when no safeguards are in place preventing genomic decay.

Comment by Bradford — August 17, 2007 @ 2:49 pm

Doug Says:
August 17th, 2007 at 2:49 pm
Why do you need a secondary function to conserve the gene if the primary function does the trick already?

But before this:

Just because the absence of RecA in the presence of UV light hinders/alters the bacterias vitality, this does not mean that the absence of RecA abolishes the bacterias vitality (i.e. is lethal).

You sound confused. So what point are you going to argue.

Comment by Doug — August 17, 2007 @ 2:49 pm

hrun Says:
August 17th, 2007 at 4:00 pm
Doug, I'm not confused at all. RecA deletion is not lethal, however, it does confer significant selective advantage to bacteria in the wild. Thus, the primary function of RecA in DNA repair already acts to conserve RecA in organisms that are exposed to DNA damaging agents. Why look for a secondary function to explain the conservation of RecA?

To spell it out slowly: Conservation of genes is not dependent on the absence of the gene being lethal.

Comment by hrun — August 17, 2007 @ 4:00 pm

Thought Provoker Says:
August 17th, 2007 at 4:22 pm
Hi Mike,

You wrote…

If the recA gene is an evolution gene, we would predict that its removal would somehow negatively impact the ability to evolve. So let's see what happens when RecA function is removed by mutation.

At the risk of exposing my lack of understanding by oversimplifying this…

Supposed we use the "lab strain of E. coli is known as DH5alpha" which has the RecA function removed as a test group. This test group and a control group (E. coli with RecA function intact) could be exposed to very low level UV radiation and some kind of environmental pressure.

It would be expected that the DH5alpha would mutate more often because of the lack of the RecA repair function. Therefore, based on RM+NS, the test group should evolve faster in response to the environmental pressure (at a predictable rate). If the evolutionary rate is significantly lower than predicted then wouldn't that suggest the recA gene is directly involved in supporting beneficial mutations (i.e. an evolution gene)?

Yea! More Science!

Comment by Thought Provoker — August 17, 2007 @ 4:22 pm

Doug Says:
August 17th, 2007 at 4:30 pm
Conservation of genes is not dependent on the absence of the gene being lethal.

Have you read Mike's article?
Hrun, you're not saying anything that hasn't been addressed in RecA Over Time.
But what you do seem to be forgetting is the degree of conservation over such disparate species: E.coli and B. subtilis.

As well as Mike's comment in a more complete context:

If we couple the way RecA is dispensable for life and reproduction in single-celled organisms to the widespread distribution of the gene and strong conservation of sequence, this suggests RecA's functions are more fully realized across generations, something we would expect from an evolution gene.

Your admission of the mild case of conservation not being dependent on the lethality (~~look at me… I'm a regular William Whewell. Or this is actually a word?~~ I'm not a regular William Whewell, it's already a word) of a genes absence does not account for the degree of conservation that was well noted in the original article.
So…. back to my initial question.

Comment by Doug — August 17, 2007 @ 4:30 pm

hrun Says:
August 17th, 2007 at 5:27 pm
Doug, I have indeed read Mike's article. Irrespective of the presence of the article, you seemed confused about RecA. Otherwise, you would not have written that RecA deletion "does not seem to hinder the bacteria's vitality." Deletion of RecA DOES seem to hinder the bacteria's vitality.

In your view, this decrease in 'vitality' (or fitness) apparently is too mild to count for the conservation of RecA among species and you are therefor looking for a secondary (presumably more important) function of RecA. How do you know that the decreased fitness or RecA deficient bacteria strains due to their inability to repair naturally occurring DNA damage is insufficient to cause this kind of conservation?

Comment by hrun — August 17, 2007 @ 5:27 pm

Doug Says:
August 17th, 2007 at 5:42 pm
Hrun,

I was refering to the fact that (as stated in the article) the bacteria were still able to survive and reproduce in the absence of a functional RecA. Are you claiming this is incorrect?
Or that eukaryotes without Rad51 are still viable. Are you claiming that this is incorrect?

Does is warrant you pulling a Bette Midler with your –

This is of course utterly incorrect.

Also,

In your view, this decrease in 'vitality' (or fitness) apparently is too mild to count for the conservation of RecA among species

Did I say that?

Or did I say:

But what you do seem to be forgetting is the degree of conservation over such disparate species: E.coli and B. subtilis.

Comment by Doug — August 17, 2007 @ 5:42 pm

hrun Says:
August 17th, 2007 at 6:25 pm
Doug, you claimed that deletion of RecA "does not seem to hinder the bacteria's vitality."

This is incorrect. Deletion of RecA does significantly hinder the vitality of numerous bacteria.

Next you wondered what the secondary function of RecA is "that allows it to be conserved?"

I still don't understand why a secondary function of RecA would be required to allow RecA to be conserved. Can you explain? Why is in your view the sensitivity to DNA damage induced by e.g. UV light insufficient to "explain the degree of conservation over such disparate species: E.coli and B. subtilis"

Comment by hrun — August 17, 2007 @ 6:25 pm

Bradford Says:
August 17th, 2007 at 6:42 pm
Deletion of RecA does significantly hinder the vitality of numerous bacteria.

The ones referred to by Mike had undergone severe genomic reduction typical of unicellular parasitic organisms. Tracing a line of descent to eukaryotes would include organisms not having suffered RecA deletion.

Comment by Bradford — August 17, 2007 @ 6:42 pm

Nick Says:
August 20th, 2007 at 9:14 am
Based on hrun and Doug's discussion, I think the critical parts of MikeGene's argument are as follows:

To start off, it does not appear RecA function is essential to unicellular life or reproduction. For example, a commonly used lab strain of E. coli is known as DH5alpha. This strain has a mutation in its recA gene such that it cannot carry out recombination.

and

If we couple the way RecA is dispensable for life and reproduction in single-celled organisms to the widespread distribution of the gene and strong conservation of sequence, this suggests RecA's functions are more fully realized across generations, something we would expect from an evolution gene.

First, I would modify MikeGene's first sentence to read: "To start off, it does not appear RecA function is essential to unicellular life or reproduction in a laboratory environment." Phenotypes always exist in an specific environment, not as some sort of ideal platonic form.

There are a great many mutations which are viable in a controlled laboratory but which would be very deleterious, if not immediately lethal, in "the field." The obvious dramatic examples are mutations in genes required for sugar metabolism or amino acid synthesis that are lethal in a natural environment but that can be "replaced" by nutritional supplements in the lab. Loss of RecA is obviously not as rapidly lethal as a mutation that prevents digestion of naturally occurring sugars, but we don't know whether DH5alpha would be capable of surviving for very long outside a petri dish. The naturally occurring RecA deletions come from highly controlled environments that are somewhat similar to a laboratory petri dish: an endosymbiont is unlikely to face the degree of environmental stress that is experienced by a free-living bacterium.

Second, although Mike points out the degree of conservation among RecA genes of different bacteria, that doesn't tell us much in and of itself. We need to determine if the level of conservation in RecA is greater than we would expect for a gene that is very important but not absolutely required in all environments. If the level of RecA conservation is in the same ball park as other genes that can be deleted in lab strains but are vital in wild strains, then there is no support for the hypothesis that RecA is an "evolution gene."

That RecA can be deleted in lab strains does not tell us anything about the degree of selection against RecA mutants in the wild. I think that's where Doug is a bit confused. Given the information in MikeGene's essay, there is not yet any need to propose any secondary function for RecA. If Mike were to provide additional data showing that the level of RecA conservation is anomalous, then it might be time to speculate about additional roles for RecA.

Comment by Nick — August 20, 2007 @ 9:14 am

MikeGene Says:
August 20th, 2007 at 9:48 am
Hi Nick,

First, I would modify MikeGene's first sentence to read: "To start off, it does not appear RecA function is essential to unicellular life or reproduction in a laboratory environment." Phenotypes always exist in an specific environment, not as some sort of ideal platonic form.

Indeed. But nevertheless, it would seem rather trivial to note that the ability to be alive and reproduce is not dependent on recombination. What recombination does is to extend that ability over time precisely because those abilities are to play out in a complex environment.

Second, although Mike points out the degree of conservation among RecA genes of different bacteria, that doesn't tell us much in and of itself. We need to determine if the level of conservation in RecA is greater than we would expect for a gene that is very important but not absolutely required in all environments. If the level of RecA conservation is in the same ball park as other genes that can be deleted in lab strains but are vital in wild strains, then there is no support for the hypothesis that RecA is an "evolution gene."

Those would be nice experiments to produce additional support for the ID hypothesis, although one would have to control for levels of redundancy when picking candidates from lab deletions. But there is already support for the hypothesis that RecA is an evolution gene: it is ubiquitous, ancient, and plays a key role in the important and evolutionarily significant process of recombination. Also, the endosymbionts suggest that it can act like a switch when it comes to genomic integrity over time.

That RecA can be deleted in lab strains does not tell us anything about the degree of selection against RecA mutants in the wild. I think that's where Doug is a bit confused. Given the information in MikeGene's essay, there is not yet any need to propose any secondary function for RecA. If Mike were to provide additional data showing that the level of RecA conservation is anomalous, then it might be time to speculate about additional roles for RecA.

My essay does not raise a secondary function. Instead, it raises an alternative perspective, where "RecA's functions are more fully realized across generations, something we would expect from an evolution gene." In other words, it's a question of observational scale. If, for some reason, we were restricted to making observations on the scale of milliseconds, we might be under the impression that RecA's function is to bind ATP, because the DNA repair functions of RecA are dependent on more time and other machinery. Thus, I'm raising a perspective that expands time even further, noting that DNA repair and recombination (what we measure in the lab) is part of the evolution-function of the gene (how an observer with a larger time frame might see it). Whether you agree or not is irrelevant. What is relevant is that this teleological perspective can ask questions, raise new thoughts, and perhaps guide research.

Comment by MikeGene — August 20, 2007 @ 9:48 am

Nick Says:
August 20th, 2007 at 10:31 am
Mike:
My essay does not raise a secondary function.

No, but Doug did, and he seemed not to understand that a gene could be highly conserved and yet not be absolutely required for life. I was responding to doug and hrun's ongoing argument, rather than to you directly.

Thus, I'm raising a perspective that expands time even further, noting that DNA repair and recombination (what we measure in the lab) is part of the evolution-function of the gene (how an observer with a larger time frame might see it). Whether you agree or not is irrelevant. What is relevant is that this teleological perspective can ask questions, raise new thoughts, and perhaps guide research.

I have no problem with viewing RecA on a larger timescale. The data that you have presented, including the loss of RecA preceding genome reduction in endosymbiotes, is fully compatible with a teleological viewpoint (evolution as a goal of RecA function) or nonteleological (RecA as a requirement for evolution), and I don't see that the teleological view raises any new issues with regard to RecA function. Teleology seems largely irrelevant in this case.

Comment by Nick — August 20, 2007 @ 10:31 am

Rock Says:
August 20th, 2007 at 10:54 am
Recombination also extends effectively (doubles) the utilization of a critical resource: random variation.

RecA is multi-functional. Reuse, co-option and multi-functions are commonly employed design techniques. But I wouldn't call it a "secondary function" especially as variation, obviously, is critical to evolution.

Therefore, if anything counts as an "evolution gene" (not a new idea, btw, in evolutionary biology) RecA must. No?

Comment by Rock — August 20, 2007 @ 10:54 am

Rock Says:
August 20th, 2007 at 11:05 am
Nick Says: The data that you have presented, including the loss of RecA preceding genome reduction in endosymbiotes, is fully compatible with a teleological viewpoint (evolution as a goal of RecA function) or nonteleological (RecA as a requirement for evolution), and I don't see that the teleological view raises any new issues with regard to RecA function. Teleology seems largely irrelevant in this case.

Wait a sec! Why is "evolution as a goal of RecA function" teleological and "RecA as a requirement for evolution" nonteleological? I don't see what the difference is between the two statements. What did substituting "requirement" for "goal" do here? Nothing? Seems rather that "nonteleology" is irrelevant in this case.

(Mike Gene knows our "dirty little secret," Nick: Evolutionary biology is suffused with teleologies, designs, mentalities, and vitalities, formal and final causes, and all that spooky stuff. Always has been and always will be.)

Comment by Rock — August 20, 2007 @ 11:05 am

MikeGene Says:
August 20th, 2007 at 11:33 am
Hi Nick,

I have no problem with viewing RecA on a larger timescale. The data that you have presented, including the loss of RecA preceding genome reduction in endosymbiotes, is fully compatible with a teleological viewpoint (evolution as a goal of RecA function) or nonteleological (RecA as a requirement for evolution), and I don't see that the teleological view raises any new issues with regard to RecA function. Teleology seems largely irrelevant in this case.

Teleology will always seem irrelevant to a non-teleological perspective, unless there is some sensational and revolutionary discovery that cannot possibly fit in the non-teleological perspective. But I don't think teleologists are obligated to come up with such a discovery, especially when non-teleologists have long become dependent on our terms and concepts. What matters at this point is not whether the teleological view raises any new issues with regard to RecA function, but whether we all must rely on the non-teleological view when contemplating and exploring something like RecA.

One thing I can say with certainty "“ I find this ID thinking to not only be fun, but actually quite stimulating. If I simply dismissed ID thinking as convention says I must, Carroll's book would have been just another interesting read about evolution. Yet ID thinking allowed me to view this book as a springboard that in turn allowed me to make connections I would not have made otherwise (and as far as I can see, not many others are making).

Anyway, as I promised over at the DM, there is more fun to come. Crank it up!

Comment by MikeGene — August 20, 2007 @ 11:33 am

Bradford Says:
August 20th, 2007 at 12:16 pm
Rock:

Wait a sec! Why is "evolution as a goal of RecA function" teleological and "RecA as a requirement for evolution" nonteleological? I don't see what the difference is between the two statements. What did substituting "requirement" for "goal" do here? Nothing? Seems rather that "nonteleology" is irrelevant in this case.

(Mike Gene knows our "dirty little secret," Nick: Evolutionary biology is suffused with teleologies, designs, mentalities, and vitalities, formal and final causes, and all that spooky stuff. Always has been and always will be.)

Rock is pointing out that teleology deniers employ teleology themselves without crediting it.:grin:

Comment by Bradford — August 20, 2007 @ 12:16 pm

Doug Says:
August 20th, 2007 at 12:26 pm
If I was wrong I apologize.
I was assuming that RecA needed a second level function in order for its integrity to be maintained across such disparate species.
I understand hrun's point and if I was wrong for assuming that there must be some other secondary function to ensure that it was conserved to the degree it has been then I stand corrected.

Comment by Doug — August 20, 2007 @ 12:26 pm

Nick Says:
August 20th, 2007 at 12:35 pm
Rock:
Wait a sec! Why is "evolution as a goal of RecA function" teleological and "RecA as a requirement for evolution" nonteleological? I don't see what the difference is between the two statements.

One statement focuses on goals and purposes. The other focuses on consequences. The statements are not symmetrical, because there can be consequences without goals.

Try this:

1. Sea ice is required for polar bear survival.

2. Polar bear survival is the goal of sea ice formation.

Statement 2. is explicitly teleological. Statement 1 is nonteleological. If 2 is true, 1 may also be true, but there are situations where 2 is false but 1 is still true.

Seems rather that "nonteleology" is irrelevant in this case.

More or less, but that's an odd way to state it. Teleology or lack thereof seems irrelevant in the evolutionary scenario that MikeGene has outlined.

Comment by Nick — August 20, 2007 @ 12:35 pm

Bradford Says:
August 20th, 2007 at 12:57 pm
Rock:
Wait a sec! Why is "evolution as a goal of RecA function" teleological and "RecA as a requirement for evolution" nonteleological? I don't see what the difference is between the two statements.

Nick:
One statement focuses on goals and purposes. The other focuses on consequences. The statements are not symmetrical, because there can be consequences without goals.

In a long chain of physical events spanning long time periods biological processes, when viewed in isolation, appear like the cited ice formation. Whether this is actually the case can be traced to conditions and events present at the begining of the chain. If mechanisms enabling an adaptation through genetic modification process were the product of teleology then all subsequent events in the chain were fruits of teleology and non-teleology is the mirage.

Comment by Bradford — August 20, 2007 @ 12:57 pm

Rock Says:
August 20th, 2007 at 2:56 pm
Sorry, Nick, that didn't help me much. Goals and purposes are both consequences and consequential, and there certainly can be consequences w/o goals and goals w/o consequences.

Nick, it almost sounds as if "teleology" is something that comes and goes depending on my choice of language or how I formulate statements. By some circumlocution, policing my vocabulary, rephrasing statements, etc. the "teleology" seems to come and go at will. All that does is substitute synonyms, but never their antonyms or some "mythical" theoretically-neutral language.

The problem with the "eliminativist" argument is that it eliminates itself. Worse, because it is nothing more than an extreme form of nominalism, it eliminates science.

It didn't occur to say that the polar bear's goal is survival. Instead it occurs to say sea water has the goal of forming ice. So the first, problem, Nick, or so it seems to me, is to determine if words like "goal," "purpose," "requirement," and even "consequence" have any meaning in the context of evolutionary biology. It goes w/o saying, does it not?

Because teleology is a theory of causation, Bradford, it suffers the same fate of all theories of causation: the infinite regress. Scientists typically and quite productively avoid the problem by exploring analytically truncated causal trains. Such an approach, as Mike Gene suggests (and if he allows) would note that the polar bear's goal is to survive and that is certainly a causal factor in any realistic evaluation of the co-evolution of, the relationship between polar bears and arctic environments.
The question about the goal of sea water to form ice to support the life of polar bears could probably be left to any scientist who finds questions about the goals of sea water interesting to explore.

Comment by Rock — August 20, 2007 @ 2:56 pm

Rock Says:
August 20th, 2007 at 3:21 pm
I should say, Bradford, that only circular causal sequences admit anything approaching complete analysis. (W/o arbitrarily cutting causal chains.)They are also the key to understanding "teleology." Scientists' notions of causality are intrinsically circular, agent-based, and assume teleology! Non-teleology is non-relevant to science.
Teleology is science's theory of causation. You can't explain sciece itself w/o teleology!

Comment by Rock — August 20, 2007 @ 3:21 pm

Rock Says:
August 20th, 2007 at 5:21 pm
Functional ("teleological") explanations represent a true problem, esp. when functions are complex, and that almost always means, dual or multiple functions are involved; or as Bradford says, a long and complex (typically defying) analysis is involved in understanding the (even simple) function.

What is the primary, principal, proper function of RecA? Is it recombination? Or is its primary function to induce variation?

Mike Gene?

Nick?

Comment by Rock — August 20, 2007 @ 5:21 pm

Doug Says:
August 20th, 2007 at 5:48 pm
I said initially:

If I was wrong I apologize.
I was assuming that RecA needed a second level function in order for its integrity to be maintained across such disparate species.
I understand hrun's point and if I was wrong for assuming that there must be some other secondary function to ensure that it was conserved to the degree it has been then I stand corrected.

From Evolution Genes:

If evolution is a process that occurs through deep time, any evolution gene would require a secondary function that allowed it to be maintained generation to generation. This would mean evolution genes will be biochemically and genetically detected through their secondary functions.

This is what I was initially asking: If RecA is important to bacteria, but bacteria can live without (but still confering a selective advantage on those that do have it) is recombination the secondary function that allows it to be maintained generation to generation. If it's the primary function, then what is the secondary function that allows it to be maintained generation to generation.

Comment by Doug — August 20, 2007 @ 5:48 pm

Rock Says:
August 20th, 2007 at 6:35 pm
I think you were wrong to apologize, Doug, "˜cuz you got the question right!

Some people think science is all about the right answers. But we know better"”It's all about the right questions. LOL

Comment by Rock — August 20, 2007 @ 6:35 pm

MikeGene Says:
August 21st, 2007 at 5:35 pm
Hi Rock,

What is the primary, principal, proper function of RecA? Is it recombination? Or is its primary function to induce variation?

I'd say those were effectively the same thing. Anyway, here's the official version.

I remember first learning about meiosis (I mean when I really learned it, not memorized it). It always seemed to me that not only was it a way to go from diploid to haploid, but it seemed to be set up precisely to let recombination play out.

Comment by MikeGene — August 21, 2007 @ 5:35 pm

Evolution Genes: The Story Continues

34 Responses to “Evolution Genes: The Story Continues”

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