What is the significance of this experiment?

[BioStudent]

So this experiment has been running for a long time, but I just found it and thought it would be interesting to hear what people think about it.

I haven't posted enought to link to the page directly, but the experiment can be found by googling "lenski experiment e.coli", and their wikipedia page is called "Escherichia coli long-term evolution experiment". If someone could post a link I'd be much obliged.

To me, it seems to be one of the clearest demonstrations of evolution in action as well as some fairly damning evidence against the argument of irreducible complexity (since the baceria began to utilize a new carbon source using a complex metabolic process).

If anyone disagrees, please explain why, preferably referencing specifics of this experiment and avoiding general statements.

 

[LuisDantas]

I take it that you mean this?

E. coli Long-term Experimental Evolution Project Site

Edited to add: and the Wikipedia article:

http://en.wikipedia.org/wiki/Escherichia_coli_long-term_evolution_experiment

 

[BioStudent]

Yeah, thanks! ...though the wiki page may be more accessible to those wanting to get the gist of the project quickly.

 

[George-ananda]

So this experiment has been running for a long time, but I just found it and thought it would be interesting to hear what people think about it.

I haven't posted enought to link to the page directly, but the experiment can be found by googling "lenski experiment e.coli", and their wikipedia page is called "Escherichia coli long-term evolution experiment". If someone could post a link I'd be much obliged.

To me, it seems to be one of the clearest demonstrations of evolution in action as well as some fairly damning evidence against the argument of irreducible complexity (since the baceria began to utilize a new carbon source using a complex metabolic process).

If anyone disagrees, please explain why, preferably referencing specifics of this experiment and avoiding general statements.

I'll first admit I'm not knowledgeable enough to agree or disagree.

I think I have a lay-man's understanding of 'irreducible complexity'.

Are you saying that this new 'complex metabolic process' came to be stage-by-stage or suddenly. I think you are saying more 'suddenly'. If so, I might have a follow-up point/question.

 

[freethinker44]

Yeah, but how does this explain how a cat can give birth to a dog? Unless evolutionists can explain that, I call BS. You can't explain why the tides go in and out, no one can. Godidit.

 

[BioStudent]

Are you saying that this new 'complex metabolic process' came to be stage-by-stage or suddenly. I think you are saying more 'suddenly'. If so, I might have a follow-up point/question.

So this is what the researchers found: sometime between the 31,00th and 31,500th generation the bacteria became able to use citrate for meatabolism. Normally, E.coli bacteria cannot do this bacause they lack protein(s) (for which genes are the blueprints) to bring the citrate inside the bacterium, where it is used.

Any sample from the 31,00th generation, when growm with citrate in the environment, will have individuals that develop the ability to use citrate. Samples from before the 20,000th generation will not develop this ability. The scientiscts think that this is beacuse, sometime between the 20,000th and 31,000th generation, a mutation appeared which "primed" the bacteria, greatly raising the probability that a second mutation would allow them to use citrate.

The ability to bring citrate into the cell is all-or-none. There is no gentle ramping up of this ability; either the bacteria can use citrate, or thay can't.

I hope this clarifies my prevoius post! and please let me know if my explanations are too technical, I'm sorry if they are and will rephrase!

 

[Revoltingest]

Yeah, but how does this explain how a cat can give birth to a dog? Unless evolutionists can explain that, I call BS. You can't explain why the tides go in and out, no one can. Godidit.

Hmmmm...it occurs to me that I've never heard this question asked....
How can a wolf give birth to a chihuahua?

 

[George-ananda]

So this is what the researchers found: sometime between the 31,00th and 31,500th generation the bacteria became able to use citrate for meatabolism. Normally, E.coli bacteria cannot do this bacause they lack protein(s) (for which genes are the blueprints) to bring the citrate inside the bacterium, where it is used.

Any sample from the 31,00th generation, when growm with citrate in the environment, will have individuals that develop the ability to use citrate. Samples from before the 20,000th generation will not develop this ability. The scientiscts think that this is beacuse, sometime between the 20,000th and 31,000th generation, a mutation appeared which "primed" the bacteria, greatly raising the probability that a second mutation would allow them to use citrate.

The ability to bring citrate into the cell is all-or-none. There is no gentle ramping up of this ability; either the bacteria can use citrate, or thay can't.

I hope this clarifies my prevoius post! and please let me know if my explanations are too technical, I'm sorry if they are and will rephrase!

Thank you very much for taking time to explain. I'm quite interested.

I think you're saying this is a two-stage process? The first 'priming' mutation took place between 20,000 and 31,000. WHY did this first priming mutation occur and get fixed if it had no benefit at that time? Would it have happened with or without the presence of citrate?

 

[BioStudent]

WHY did this first priming mutation occur and get fixed if it had no benefit at that time? Would it have happened with or without the presence of citrate?

This is just an assumption, but I would say maybe it had an alternate benefit? They are trying to figure out what it actually changed atm. It does not have to be beneficial to the citrate process specifically. The mutation would have happened with or without citrate, but whether it would have gotten fixed depends on what it changes in the cell.

Alternately, it was a neutral mutation that had no effect on the bacterium and was only present in the part of the population dscended from whatever cell got it, and it is from that portion that the citrate-using bacteria came.

At this point these are my thoughts based on what I know of biology (I'm not an expert, though I am currently majoring in it). I haven't found what the original researchers think, it seems like they are trying to figure this out right now.


EDIT: I just found a paper from 2012 that discusses what happened witht the two mutations. So a gene allowing metabolism of citrate in other conditions not present in the experiment (This gene was always present in the bacteria), was duplicated, allowing them to metabolize citrate under the conditions of the experiment, but very ineffciently. This was advantageous, but a very small amount <1%. The second mutation made even more copies of those genes, which gave enough of an advantage that the bacteria that had it became dominant in the population. Then, later mutations (after the initial study I mentioned was published) refined the proteins involved further so they worked better.

 

[Sculelos]

Hmmmm...it occurs to me that I've never heard this question asked....
How can a wolf give birth to a chihuahua?

RNA variation, granted going from a 100lb Wolf to a 7lb Chihuahua would most likely take at least 32 generations to breed a Wolf into a Chihuahua.

If a person could theoretically live to say 100 and they breed dogs their whole life it's feasible that you could breed a Wolf to a Chihuahua in 80 years.

But then again, Dogs do breed much faster then Humans and they are often breed for certain qualities so it's quite natural to see close to the maximum RNA variety possible in Dogs.

However we still haven't got to the 80 inch tall Wolfs like they used to have 'Back in the Day'

 

[ImmortalFlame]

RNA variation, granted going from a 100lb Wolf to a 7lb Chihuahua would most likely take at least 32 generations to breed a Wolf into a Chihuahua.

If a person could theoretically live to say 100 and they breed dogs their whole life it's feasible that you could breed a Wolf to a Chihuahua in 80 years.

But then again, Dogs do breed much faster then Humans and they are often breed for certain qualities so it's quite natural to see close to the maximum RNA variety possible in Dogs.

However we still haven't got to the 80 inch tall Wolfs like they used to have 'Back in the Day'

I think this post just gave me a form of intellectual whiplash...

 

[BioStudent]

RNA variation, granted going from a 100lb Wolf to a 7lb Chihuahua would most likely take at least 32 generations to breed a Wolf into a Chihuahua.

Um, I don't really understand what you mean in most of your post, however I would like to point out that RNA is sorta like a temporary copy of DNA that only exists for a short time, so if there is variation between the RNA two organisms produce, it means there is a difference in their DNA.

 

[Ouroboros]

To me, it seems to be one of the clearest demonstrations of evolution in action as well as some fairly damning evidence against the argument of irreducible complexity (since the baceria began to utilize a new carbon source using a complex metabolic process).

I read about this experiment a couple of years ago. And yes, it does show that irreducible complex genetic mutation can happen naturally.

The core flaw in the "irreducible complex" argument is that there's this notion that a mutation always must be extremely beneficial to an organism for it to hang around in the gene pool. It's not the case. We all have many genes in our DNA that is either turned off (dormant), harmless, or only slightly damaging. For instance, if a person has a gene that makes their teeth slowly rot and fall out by the age of 50, it won't stop that person from reproduction or even success. Irreducible complexity is argued from the standpoint that there can't be a set of different genes producing different non-functional proteins that in a future generation could suddenly be beneficial under yet another mutation.

For instance, we all humans carry a faulty gene for C-vitamin production. The gene produces a non-functional C-vitamin. It's not selected against because we eat fruit, and the same goes for chimps. Both chimps and humans get their source of C from the food and the gene is not detrimental , unless we try to travel on a boat without necessary supplies (scurvy).

 

[Ouroboros]

I'll first admit I'm not knowledgeable enough to agree or disagree.

I think I have a lay-man's understanding of 'irreducible complexity'.

Are you saying that this new 'complex metabolic process' came to be stage-by-stage or suddenly. I think you are saying more 'suddenly'. If so, I might have a follow-up point/question.

What happened was that somewhere around 50,000 generations, the E-Coli developed a way of metabolize that required two (2) different genetic changes. They went back in the earlier generations and found that many generations earlier, one of the gene changes had occurred, and at 50,000 the next one necessary occurred. (Something like that. I'm trying to recall from memory.)

According to Behe and the Irreducible Complex camp, this can't happen... at all... ever... but it did.

 

[Ouroboros]

Yeah, but how does this explain how a cat can give birth to a dog? Unless evolutionists can explain that, I call BS. You can't explain why the tides go in and out, no one can. Godidit.

And no one can explain where beer goes. I buy all these bottles and then they're gone... Godidit.

I think some creationists should go to some of the larger zoos and look at all the weird animals that exist. There are some species that don't look like anything else, but rather a mix of other animals.

 

[Ouroboros]

Thank you very much for taking time to explain. I'm quite interested.

I think you're saying this is a two-stage process? The first 'priming' mutation took place between 20,000 and 31,000. WHY did this first priming mutation occur and get fixed if it had no benefit at that time? Would it have happened with or without the presence of citrate?

The problem with the notion of "survival of the fittest" is that people seems to think that genes must be only beneficial to survive. There are many mutations that occur that are neutral. A gene doesn't have to be selected for or against if it doesn't affect reproduction or success.

At some point, one bacteria had the first mutation. It wasn't detrimental to its survival, but probably didn't do anything at all. Over time, by simple distribution, that bacteria's "offspring" probably had a larger representation in numbers, but not overwhelming. Then one in that group had another mutation, that just fit for the next step.

For anyone who thinks this can't happen... well, sorry, but it did.

 

[Sculelos]

Um, I don't really understand what you mean in most of your post, however I would like to point out that RNA is sorta like a temporary copy of DNA that only exists for a short time, so if there is variation between the RNA two organisms produce, it means there is a difference in their DNA.

DNA is basically a burned in copy and RNA is a copy that adapts based on environmental factors. You will never see DNA change but you will always see RNA change so basically variety is limited to the hard limits placed in DNA however RNA can be very strange at time. RNA if it wanted to could cover the entire human body with hair.

http://en.wikipedia.org/wiki/Hypertrichosis

 

[BioStudent]

DNA is basically a burned in copy and RNA is a copy that adapts based on environmental factors. You will never see DNA change but you will always see RNA change so basically variety is limited to the hard limits placed in DNA however RNA can be very strange at time. RNA if it wanted to could cover the entire human body with hair.

I'm not a doctor or even a med student, but, based solely on my impression of the wikipedia article, acquired hypertrichosis is linked to cancer (which is caused by mutations in DNA, not RNA). If you meant the inherited form, it is caused by mutations in the DNA of the parent from whom it was inherited.

(If someone better qualified knows this to be incorrect please correct me!)

As far as I know, RNA simply does not exist long enough in the body for a change in the RNA sequence to have a long-lasting physiological effect. RNA does not, as a rule, change indvidually of DNA, because every piece of RNA is copied from the parent DNA strand, never from other RNA, so changes cannot accumulate and are destroyed with the "mutant" RNA (which is rather quickly in terms of the organism's lifetime).

 

[Sculelos]

I'm not a doctor or even a med student, but, based solely on my impression of the wikipedia article, acquired hypertrichosis is linked to cancer (which is caused by mutations in DNA, not RNA). If you meant the inherited form, it is caused by mutations in the DNA of the parent from whom it was inherited.

(If someone better qualified knows this to be incorrect please correct me!)

As far as I know, RNA simply does not exist long enough in the body for a change in the RNA sequence to have a long-lasting physiological effect. RNA does not, as a rule, change indvidually of DNA, because every piece of RNA is copied from the parent DNA strand, never from other RNA, so changes cannot accumulate and are destroyed with the "mutant" RNA (which is rather quickly in terms of the organism's lifetime).

RNA is basically diversions from what DNA states but it is recessive which means there is about a 25% chance of it being passed on to offspring however that chance can jump to 100% if the RNA damage is due to a natural cause like living next to a volcano can cause your skin to darken if done for several generations in a row. This is not due to DNA because DNA can vary from near albino to almost a charcoal black. However it's bad science to say that the Environment doesn't have a very large effect on RNA. Personal habits will make certain RNA traits more pronounced however it does take time and it doesn't pass on at a 1:1 ratio but more of a 1:4 ratio however if enough people get a certain trait the trait will certainly be passed on as eventually all will have the active RNA gene attached to their DNA.

 

[FranklinMichaelV.3]

RNA is basically diversions from what DNA states but it is recessive which means there is about a 25% chance of it being passed on to offspring however that chance can jump to 100% if the RNA damage is due to a natural cause like living next to a volcano can cause your skin to darken if done for several generations in a row. This is not due to DNA because DNA can vary from near albino to almost a charcoal black. However it's bad science to say that the Environment doesn't have a very large effect on RNA. Personal habits will make certain RNA traits more pronounced however it does take time and it doesn't pass on at a 1:1 ratio but more of a 1:4 ratio however if enough people get a certain trait the trait will certainly be passed on as eventually all will have the active RNA gene attached to their DNA.

No...this is so wrong...I don't even...:run: