Evolution, Evolution, Evolution

[Gawron]

Posted by Naraoia:

“DNA repair systems are not 100% error-proof! NOTHING in biology is!”

No, but I have always thought that one legitimate point those who argue against evolution can and have made is the consequence of those errors. I am confident you are familiar with the term “mutator” phenotype and how one is formed. However, for those who are not as is my habit a brief background.

When the mechanisms which help ensure the stability of DNA replication fail to function properly, or when the gene products responsible for said mechanisms fail or are inactivated, the result is an increased rate of mutation known as a “mutator” phenotype. Frameshifts and Transversions are two examples of a “mutator” phenotype.

As of late the accuracy with which DNA replicates can be fairly easily measured. One manner in which it is measured is errors per nucleotide sequence. Using bacterial reproduction as an example, according to the Campbell, Reece, and Mitchell fifth edition text Biology, without a repair mechanism in place, mutations would occur at the rate of 10-3 (sorry, read ten to the negative third power) as opposed to the often stated rate of 1 error/genome/1000 bacterial replications.

So, if one or more of these errors leads to a mutator phenotype, a transversion can occur among base pairs such as GC to TA. All well and good.

But what are the results of such faults in the repair systems, of a mutator phenotype? This has been argued and debated within the constructs of evolutionary theory countless times. Those on one side categorically state that over gazillions of years (just being trite) positive mutations add up which are passed through the germ line and quadrapeds become whales. Those on the other side state that since most mutations are lethal, there is a hole in the theory, in that mutations which are deleterious to the organism will usually destroy the organism. Vast amounts of time verses the usual lethality of genetic mutations.

I do know the arguments, I don’t claim to have all the answers. I just find the question an interesting one, especially in light of such mechanisms as oncogenes and tumor suppressor genes and their respective functions, and this in light of finding claims that cancerous cellular degeneration is being hailed as a Darwinian form of mutation.

I am researching this last tonight, and if anyone is interested I will post links on it later. As a result of a medical issue at home I rarely have time to post here, but I am glad I have a little time now. Most of you guys are alright.

 

[Naraoia]

Been away for awhile, but noticed I had posted once on this thread and decided to re-examine. I agree with Naraoia on one thing. Wow.

Welcome back!

When the mechanisms which help ensure the stability of DNA replication fail to function properly, or when the gene products responsible for said mechanisms fail or are inactivated, the result is an increased rate of mutation known as a “mutator” phenotype. Frameshifts and Transversions are two examples of a “mutator” phenotype.

Frame shifts and transversions are two examples of types of mutation, not of mutator phenotypes.

(I'm not entirely sure why you highlight them separately, though... are they disproportionately enriched in mutators compared to other mutations? Or do they have some other significance? I can't think of any important way other than frequency that transversions differ from transitions. )

As of late the accuracy with which DNA replicates can be fairly easily measured. One manner in which it is measured is errors per nucleotide sequence. Using bacterial reproduction as an example, according to the Campbell, Reece, and Mitchell fifth edition text Biology, without a repair mechanism in place, mutations would occur at the rate of 10-3 (sorry, read ten to the negative third power) as opposed to the often stated rate of 1 error/genome/1000 bacterial replications.

I happen to have the 7th edition of Campbell & Reece I can only find a per gene rate with repair Which chapter/section is it in?

BTW, you can do [sup]superscripts[/sup] with [sup] and [sub]subscripts[/sub] with [sub] tags.

But what are the results of such faults in the repair systems, of a mutator phenotype? This has been argued and debated within the constructs of evolutionary theory countless times. Those on one side categorically state that over gazillions of years (just being trite) positive mutations add up which are passed through the germ line and quadrapeds become whales. Those on the other side state that since most mutations are lethal, there is a hole in the theory, in that mutations which are deleterious to the organism will usually destroy the organism. Vast amounts of time verses the usual lethality of genetic mutations.

Wait, where do mutator phenotypes come into this? The only place I've seen them mentioned in connection with evolution is bacteria under stress. I don't think I've ever encountered the idea that mutator phenotypes bring about major changes (OK, the unmasking of variation by heat shock protein dysfunction might qualify if you stretch it).

Or is that not what you're trying to say? I don't know, the whole rest of the paragraph just doesn't seem to have any obvious connection to the first sentence.

(Also, I hardly think most mutations are lethal, or even if they are, it's a barrier to evolution. Variation, both neutral and selected, is ubiquitous in the living world. Adaptation is known to occur. While there are many intriguing and unanswered questions in evolutionary biology, I doubt that the existence of enough beneficial mutations is one of them.)

I am researching this last tonight, and if anyone is interested I will post links on it later. As a result of a medical issue at home I rarely have time to post here, but I am glad I have a little time now. Most of you guys are alright.

Cancer, you mean? I'm not sure I get what you want to say, but links to interesting stuff are always welcome.

 

[lucaspa]

But what are the results of such faults in the repair systems, of a mutator phenotype?

There are some situations in which a mutator phenotype has a selective advantage. This seems to be when the population is exposed to many very different environments in a short time. A mutator phenotype is going to generate lots of variations and one of them will work in the new environment. Some papers in the literature you will want to read are:
1. D. Grady, Quick-change pathogens gain an evolutionary advantage.Science, vol.274: 1081, 1996 (November 15). The primary research articleis JE LeClerc, B Li, WL Payne, TA Cebula, High mutation frequencies among Eschericia coli and Salmonella pathogens. Science, 274: 1208-1211, 1996 (Nov.15).
2. PB rainey and ER Moxon, When being hyper keeps you fit. Science 288: 1186-1187, May 19, 2000.

Those on the other side state that since most mutations are lethal,

That turns out to be factually incorrect. The vast majority of mutations are not lethal. By "vast" I mean 997 out of 1,000 are not lethal. Not only that, they are not even deleterious. Those 997 mutations are either beneficial or neutral:
PD Keightley and A Caballero, Genomic mutation rates for lifetime reproductive output and lifespan in Caenorhabditis elegans. Proc. Natl. Acad. Sci. USA 94: 3823-3827, 1997 (you might be able to get this one online).

So, with the premise wrong, the creationist argument is wrong.

I do know the arguments, I don’t claim to have all the answers. I just find the question an interesting one, especially in light of such mechanisms as oncogenes and tumor suppressor genes and their respective functions, and this in light of finding claims that cancerous cellular degeneration is being hailed as a Darwinian form of mutation.

First, it isn't "Darwinian form of mutation". Mutations are Mendelian .

Second, remember when most cancers occur in the 5th decade of life and older. At this point humans have had their kids. Therefore what happens here is invisible to natural selection.

As it happens, it is being recognized that one of the major problems in treating cancers is natural selection. Cancers are populations of cells. Very large populations: hundreds of millions to billions. Each cell varies. So, we come up with a cancer treatment and it kills 99.99% of the cancer cells. Great, right? Nope. That still leaves hundreds to a thousand cancer cells alive. Why? Because they had a variation that made them resistant to the treatment. So now these survivors start to divide and they pass that resistance to their offspring. Within a couple of years the cancer is back up to hundreds of millions of cells and this time, the cells won't be killed by the treatment.

Sometimes it would be nice if evolution were wrong.

 

[sfs]

Grar English teacher smash! It's a quotation. "Quote" is a verb, the noun is "quotation". Just because it's come into common usage because of laziness does not mean it's correct.

I've only just stumbled onto this thread (glad I've missed it until now), but as an old English major I have to disagree with this. If something has come into common usage, whether because of laziness or not, that does indeed mean that it's correct. There is no meaning for "correct" when it comes to definitions other than usage; definitions record and codify usage. Now it might well be that some usage serves as a marker for lower education or lack of sophistication, but that is not the same as being incorrect.

I.e., I am not a prescriptivist.

 

[Drekkan85]

I've only just stumbled onto this thread (glad I've missed it until now), but as an old English major I have to disagree with this. If something has come into common usage, whether because of laziness or not, that does indeed mean that it's correct. There is no meaning for "correct" when it comes to definitions other than usage; definitions record and codify usage. Now it might well be that some usage serves as a marker for lower education or lack of sophistication, but that is not the same as being incorrect.

I.e., I am not a prescriptivist.

Pft, next they'll be splitting their infinitives and ending sentences in prepositions! To knowingly accept that makes me wonder what this world is coming to!

 

[Hespera]

Pft, next they'll be splitting their infinitives and ending sentences in prepositions! To knowingly accept that makes me wonder what this world is coming to!

Everything is seemingly spinning out of control!

 

[Hespera]

Posted by Naraoia:

“DNA repair systems are not 100% error-proof! NOTHING in biology is!”

No, but I have always thought that one legitimate point those who argue against evolution can and have made is the consequence of those errors. I am confident you are familiar with the term “mutator” phenotype and how one is formed. However, for those who are not as is my habit a brief background.

When the mechanisms which help ensure the stability of DNA replication fail to function properly, or when the gene products responsible for said mechanisms fail or are inactivated, the result is an increased rate of mutation known as a “mutator” phenotype. Frameshifts and Transversions are two examples of a “mutator” phenotype.

As of late the accuracy with which DNA replicates can be fairly easily measured. One manner in which it is measured is errors per nucleotide sequence. Using bacterial reproduction as an example, according to the Campbell, Reece, and Mitchell fifth edition text Biology, without a repair mechanism in place, mutations would occur at the rate of 10-3 (sorry, read ten to the negative third power) as opposed to the often stated rate of 1 error/genome/1000 bacterial replications.

So, if one or more of these errors leads to a mutator phenotype, a transversion can occur among base pairs such as GC to TA. All well and good.

But what are the results of such faults in the repair systems, of a mutator phenotype? This has been argued and debated within the constructs of evolutionary theory countless times. Those on one side categorically state that over gazillions of years (just being trite) positive mutations add up which are passed through the germ line and quadrapeds become whales. Those on the other side state that since most mutations are lethal, there is a hole in the theory, in that mutations which are deleterious to the organism will usually destroy the organism. Vast amounts of time verses the usual lethality of genetic mutations.

I do know the arguments, I don’t claim to have all the answers. I just find the question an interesting one, especially in light of such mechanisms as oncogenes and tumor suppressor genes and their respective functions, and this in light of finding claims that cancerous cellular degeneration is being hailed as a Darwinian form of mutation.

I am researching this last tonight, and if anyone is interested I will post links on it later. As a result of a medical issue at home I rarely have time to post here, but I am glad I have a little time now. Most of you guys are alright.

I dont qualify as a guy or probably for your alright list either.

Please accept thought that I am sorry to hear of a medical issue at home and I hope that all is well now.

Definitely extending best wishes for you and yours.

 

[sfs]

Pft, next they'll be splitting their infinitives and ending sentences in prepositions! To knowingly accept that makes me wonder what this world is coming to!

That would be teh suck.

 

[metherion]

I saw that naraoia left some point undone, and I thought I would tackle one of them. The entire post dedicated to the life science challenge.

In a few sentences, the life science challenge goes like this:
Both of us (cre/evo sides) give 10K USD to a judge. We both go to court. If the evolution side proves evolution is science and creationism is religion, they get all of it. If the creation side proves the opposite, THEY win the 20k USD.

So, in light of Dover, that should be easy, right? Wrong. Take a look at the fine print of the FAQs page, where they define their terms.

EVOLUTION is the development of an organism from its chemicals to its primitive state
to its present state.

Well, pardner, lookie thar. It's a definition of evolution that isn't the same as the scientific definition of evolution. It in fact includes (at a glance) at least abiogenesis. Which isn't evolution. Which is irrelevant to evolution. After all, evolution requires life, so if this contest says 'evolution includes going from chemicals to primitive state to how it is now', well, that's not evolution, so the challenge is bunk, so much for THAT idea.

If you go to the website, you'll see a lot of exhortations about how since 'evolutionists' haven't come forward, they're defaulting, etc etc, so creationism wins. It's dishonest bunk and rhetoric. Nothing more. Their definition of evolution and what science says evolution is aren't the same, so claiming scientists won't come defend it is dishonest.

Metherion

 

[Naraoia]

So, in light of Dover, that should be easy, right? Wrong. Take a look at the fine print of the FAQs page, where they define their terms.

Interesting idea of fair play.

It in fact includes (at a glance) at least abiogenesis. Which isn't evolution. Which is irrelevant to evolution. After all, evolution requires life...

That point depends on the definition of life. Evolution only requires competing, imperfect replicators, so for evolution to require life, any such molecule would have to be considered alive.

N.B. I'm not saying replicators shouldn't be called alive (I'm undecided about the best way to define life), or that the challenge is fair.

 

[RyanLeeParis]

The only evidence I've heard is mainly from creatures skeletal structures looking too similar, especially ones that live near each other. This, of course, may make people think they are related somewhere down the line.

That is pretty much the evidence for evolution, in a nutshell. It is mainly from bones.

I don't personally suddenly believe in large-scale evolution producing all species on earth because of these similar bones, but that is usually the evidence they try to use.

 

[solarwave]

I think the bone evidence is just a small part of the evidence. Eg: genetics

 

[lucaspa]

The only evidence I've heard is mainly from creatures skeletal structures looking too similar, especially ones that live near each other. This, of course, may make people think they are related somewhere down the line.

That is pretty much the evidence for evolution, in a nutshell. It is mainly from bones.

Paleontology is only a small part of the evidence for evolution. And you have misstated the fossil evidence. It's not just organisms with similar skeletons that live near each other. Instead, it's a succession of individuals or species sequenced in time showing a succession of changes from one creature to another. This can be individuals linking species to species together. Or it can be a sequence of species linking higher taxa, like the sequence of species in the reptile to mammal transition.

In living species, there are species that live in adjancent geographical areas with a hybrid zone between them. This is what gave Wallace the idea for evolution back in 1858.

 

[Naraoia]

The only evidence I've heard is mainly from creatures skeletal structures looking too similar, especially ones that live near each other. This, of course, may make people think they are related somewhere down the line.

It's a bit more complicated than that. I think you could benefit from learning about the history of thought regarding fossils and/or comparative anatomy (I'm not sure which of the two you are referring to). Patterns of similarity that are used to support evolution were noted long before evolution became the dominant paradigm in biology.

(There's also a bit more to it than than "skeletal structures looking too similar")

That is pretty much the evidence for evolution, in a nutshell. It is mainly from bones.

Actually, that is wrong on more than one level. First, as lucaspa said, "bones" (whether you mean fossils or comparative anatomy) are only part of the evidence. I wouldn't say a "small" part - yes, it would probably be possible to infer evolution without them, but they really represent a huge body of evidence, replicated many many times in many many different groups of organisms, regions and time periods.

Second (this is the nitpicky criticism ), most fossils are not bones. They are shells, tubes, houses, spikes, teeth etc. belonging to the vast majority of the living world that doesn't have a backbone. Some of the neatest transitional series in the fossil record come from single-celled creatures, not even animals, let alone vertebrates. I have some issues with this book, but it's worth a look just for those transitions (unfortunately the beautiful electron micrographs of foraminifera aren't in the free preview here, but the relevant text is).

By the way, this is how much evidence exists for large-scale evolution. As you can see, it's a lot more than bones. Want to discuss any of it?

I don't personally suddenly believe in large-scale evolution producing all species on earth because of these similar bones, but that is usually the evidence they try to use.

Who are "they"?