Observing Evolution Over 40,000 Generations 461
Last year we discussed the work of Richard Lenski, who has been breeding E. coli for 21 years in a laboratory in Michigan. Then, the news was that Lenski's lab had caught direct, reproducible evidence of a genetic mutation with functional consequences for an organism. Now Lenski's lab has published in Nature a major study comparing adaptive and random genetic changes in 40,000 generations of E. coli (abstract here). "Early changes in the bacteria appeared to be largely adaptive, helping them be more successful in their environment. 'The genome was evolving along at a surprisingly constant rate, even as the adaptation of the bacteria slowed down,' [Lenski] noted. 'But then suddenly the mutation rate jumped way up, and a new dynamic relationship was established.' By generation 20,000, for example, the group found that some 45 genetic mutations had occurred, but 6,000 generations later a genetic mutation in the metabolism arose and sparked a rapid increase in the number of mutations so that by generation 40,000, some 653 mutations had occurred. Unlike the earlier changes, many of these later mutations appeared to be more random and neutral. The long-awaited findings show that calculating rates and types of evolutionary change may be even more difficult to do without a rich data set."
fuck that (Score:5, Funny)
god did it
Re:fuck that (Score:5, Insightful)
god did it
Which one of them?
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Shiva! DUH!
Everyone knows that! Just ask Buddah or Mohammed, they will tell you.
Re:fuck that (Score:4, Funny)
Is a "your mom" joke appropriate in this particular case? :>
Re:fuck that (Score:5, Funny)
god did it
Haha I thought it was funny.
It reminded me of Bill Hicks, the master of the use of comedy for the opening of minds.
"[The Earth being] 12,000 years old. I asked the guy, c'mon man, dinosaur fossils, what's the deal? He goes, 'God put those here to test our faith'. I think God put you here to test MY faith, dude. I think I figured this out. That's what this guy said -- does that bother anyone here, the idea that GGOODD might be fuckin' with our heads? Anyone have trouble sleeping restfully with that thought in their head? God's runnin' around, burying fossils, 'huh huh huh, we'll see who believes in me now! Huh huh, I'm a prankster God, I am killing me ha ha ha". You die and go before St. Peter, he says 'Did you believe in dinosaurs?' Well yeah, there were fossils everywhere! 'What are you, an idiot, God was fuckin' with you! Giant flyin' lizards, you moron, that's one of God's EASIEST jokes!' It seemed so plausible, aaaahhhhhh!"
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Geez, so was it that God character responsible for those holes in my rubbers?
Just asking.....or maybe it was that Grodd character? I keep getting them mixed up..
But on a more serious note, what Mr. Lenski did, while highly admirable contribution to science, was almost predictable, as is the case with anyone - biologically speaking - who has immersed themselves in a subject, then realizes after a few years of immersion how many more knowledge connections they now realize on said subject.
Also, as with any ae
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So god is an 8 year old smushing his finger into the petri dish trying to squish things....
I knew it!
Re:fuck that (Score:4, Funny)
I prefer this bible reading [youtube.com] :-)
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Fark, it's a trap
Creationists response: (Score:5, Funny)
Re:Creationists response: (Score:5, Informative)
51% of people believe god created man as he is.
30% said god created us and we can evolve
15% say humans evolved with out god.
These figures are a terrifying example of humans ability to deny what should be blatantly obvious. If we can do this imagine how many things people must get completely wrong no matter the level of obviousness.
Re:Creationists response: (Score:5, Insightful)
Meant as a joke but it will sadly happen like this. It is incredible that we can have this level of clear investigation into evolution. And it is something that people have innately known since early agriculture (replanting grain using the best seeds, genetic engineering). Yet in the US:
51% of people believe god created man as he is.
30% said god created us and we can evolve
15% say humans evolved with out god.
These figures are a terrifying example of humans ability to deny what should be blatantly obvious. If we can do this imagine how many things people must get completely wrong no matter the level of obviousness.
These figures are incredible examples of how much money [virtualtourist.com] you can make on peoples stupidity.
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You think that people that want to go to the Vatican Museum and see some of the worlds' greatest works of art are stupid? Wow. That is so sad. Guess you've never been to see it. Suffice it to say most people do not go to the vatican museum out of religious zeal. In fact most visitors to the museum are likely not even catholic, or even religious. The Sistine Chapel paintings are simply amazing. Sure you can look at the paintings from a religious point of view, but as artwork they stand just fine witho
Re:Creationists response: (Score:4, Insightful)
That is not entirely fair.
It's more like 45% against the 51% which is far less terrifying than you make it out to be. What about the other 4%?
I'm all for the impartial analysis of data and I fully recognize that being proven wrong can be just as valuable as being proven right.
Faith is not the enemy of Science, and therefore, the enemy of logic and reason. I have always believed that Faith is simply the believe in a hypothesis that currently lacks the ability to reach any conclusions. Science is not without Faith in that regard. Faith can be a healthy component of our existence and provide meaning, purpose, and comfort. Regardless of your opinions, it is a well used coping mechanism by the majority of the planet to deal with the very fact we exist and we have questions without answers.
The problem that you seem to have, and that I have as well, is when people who have Faith (sometimes commonly grouped into the Christian Faith) ignore all evidence in front of them and hold on to beliefs that have already been proven wrong beyond all reasonable doubt. Those people that would belligerently refuse the truth that has been revealed to them because admitting they are wrong somehow destroys their faith.
More problematic, and downright destructive and counter-productive to human growth, are those that will not only refuse to have a dynamic adaptive Faith that can change with new data and observations, but cannot accept anyone else having a Faith different than their own.
That 30% do not fall into that category necessarily are certainly not the most destructive. They are acknowledging that evolution as a process is real and observable. I cannot see how that is denying anything you hold to be "blatantly obvious". Neither you or I can prove that God does not exist and currently we have no data or observations that can disprove that God did not set into motion the creation of the Earth, and through evolutionary processes, all life on Earth. Of course, I think we have reasonably disproved the whole so-called 7 day "theory" and that Earth is only a few thousand years old. However, to me that only proves the Bible was a book created by a bunch of men with vivid imaginations. Disproving the Bible, in whole or in part, does not disprove the existence of diving being(s).
Your post is rather insulting to that 30%. I don't think they are your "enemies" in this case or part of the problem. Heck, the very fact they are willing to acknowledge Evolution means they are meeting you half way and can be reasoned with.
The 51% are probably a lost cause. That is not intended as an insult, but people can take that for what's it worth. When Faith cannot change because it has been delivered by Doctrine, than it is not really their Faith at all. I agree with you and those people concern me greatly since they seem to like laws that legislate their Faith upon others which is deeply and tragically ironic considering that my country (USA) was ostensibly founded with opposition to such behavior.
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I have no problem with people who's faith doesn't collide with science, but:
I have always believed that Faith is simply the believe in a hypothesis that currently lacks the ability to reach any conclusions.
The problem is, why chose _that_ particular hypothesis, if there is no ground to sustain it? On the other hand, we have respected scientist calling for hipothesis like the future changing the present [arxiv.org], so it's doesn't t
That's one thing I like in the Dalai Lama:
"My confidence in venturing into science lies in my basic belief that as in science, so in Buddhism, understanding the nature of reality is pursued by means of critical investigation."
"If scientific analysis were conclusively to demonstrate certain claims in Buddhism to be false," he says, "then we must accept the findings of science and abandon those claims."
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Because it makes me feel good?
I would ask the question why not? What are the reasonable grounds to sustain a hypothesis in your opinion? There are a great many aspects of spirituality and religion which certainly seem to have no scientific ground to sustain them. Yet, that in of itself does not make those beliefs negative.
Let's say I want to believe that Unicorns exist. As long as I realize that there is no evide
No, this is a creationist's response (Score:3, Interesting)
http://www.answersingenesis.org/articles/aid/v2/n1/a-poke-in-the-eye [answersingenesis.org]
"Previous research has shown that wild-type E. coli can utilize citrate when oxygen levels are low."
In some of my previous posts, I've tried to convey the idea that perhaps we're not seeing new characteristics generate - rather we're seeing a reconfiguration / recombination / whatever of existing information.
As the quote says, it already knew how to use citrate. Creationists are fine with that. I think when you look closely at each exampl
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If it is so blatantly obvious, what is your discrimination criteria between the last two options?
I mean, most people say that they can't tell, but since you take the opposite approach, I'm curious what your data is?
Oh? Just your presupposition that God doesn't exist proves that God doesn't
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Standard nonsense and moving the goal posts. 30 years ago creationists defined "macroevolution" to mean speciation. Now they use it to mean some vague broader category. Indeed, speciation at this point is so accepted that Answers in Genesis one of the largest young earth creationist ministries list the claim that speciation does not occur as an argument that creationists should not use. http://www.answersingenesis.org/get-answers/topic/arguments-we-dont-use [answersingenesis.org]. As far as I can tell, "macroevolution" when used
Re:Creationists response: (Score:5, Informative)
http://rationalwiki.com/wiki/Lenski_affair [rationalwiki.com]
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No, the difference is that the Theist makes shit up.
Everyone else relies on this little thing called logic to understand reality, rather than making up fairy tales.
Re:Creationists response: (Score:4, Insightful)
Richard Lenski could have saved himself a lot of time if he had asked himself "was any new information created when it mutated" . The answer of course is NO!
Even though you're a troll, I'm feeling generous today. This is completely and utterly wrong, and if you understood what information was, you'd agree with me — and all of biology — that evolution occurs within a species. (Speciation will have to wait for another day.)
Claude Shannon, of Bell Labs fame, invented Information Theory in the late 1940s for the utterly practical purpose of cramming more data onto copper wires. What he discovered, with a bit of a shock quite soon after, was that the equations were identical to those describing thermodynamic entropy. In fact, thermodynamic entropy turned out to be a special case of Information Theory. After discovering this, Shannon took to calling his discovery "information entropy".
Fundamentally, thermodynamic entropy is the unpredictableness of a physical system. The more unpredictable a physical system is, the more information it takes to describe the system. This was the link between the two.
About 10 years later in computer science, two researchers named Kolmogorov and Chaitin [wikipedia.org] independently invented a hypothetical measure for the complexity of any arbitrary data: measure the length of the shortest possible computer program that can produce that data. Again, random data has the highest complexity: if the data has a pattern, then a short program can compute the pattern starting from a tiny piece of the data; but if there is no pattern in the data, the program must be large enough to duplicate a full copy of the data.
Getting back to biology: mutations add randomness to DNA. Therefore, they make the DNA less predictable, and therefore they add information and complexity to the DNA. After that, natural selection acts on that mutation: if the mutation was harmful for the cell, the cell makes fewer copies of itself; if the mutation was beneficial for the cell, the cell makes more copies of itself.
(Aside: It helps that DNA duplication is a fairly common event, especially in kingdoms like the animal kingdom where virus-like transposons infect all of our genomes. If you're a cell, and you have two copies of a gene, and one copy is mutated into something useless by a mutation, then nothing bad happens to you. In fact, if having the extra copy was a bad thing, making the copy shut up or do something else is a good thing. A lot of new proteins arose because the gene coding for them was copied then modified until it finally did something useful again, like the mammal blood clotting cascade or the photoreceptor pigments for color vision.)
Natural selection provides a filter: it layers meaning on top of the information in the DNA, in much the same way that "English" is a filter that layers meaning on top of "light-emitting screen that displays funny squiggly marks". If information "A" means "cell lives", and information "B" means "cell dies", then natural selection is the process that distinguishes between "A" and "B" by giving them meaning. Information is complexity. Information is unpredictability. Information is randomness. Information is not meaning. Meaning is something you do with information, not something the information inherently has.
Once you understand the difference between "information" and "meaning", you necessarily realize that DNA was the final, unequivocal proof that microevolution logically must exist in biology and that it's silly to argue otherwise. Your beliefs are contradicted by reality itself.
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The increased population was in an artificial environment unlikely to occur in the wild.
So? It's still beneficial to the organism in its current environment.
[The genetic changes] may actually be a reduction in the information by way of damaging the mechanism used to regulate the e.coli metabolism in the presence of oxygen.
This is a much better argument than the one this thread started with. But for that scenario to work, there would have to be some reason to create and keep that inhibitory system
Someone needs to tag this "Inbreeding".. (Score:2, Insightful)
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Is that are joke or are you intentionally dense? http://en.wikipedia.org/wiki/Inbreeding [wikipedia.org]
"Inbreeding has a variety of consequences. Allele exposure can cause genes to be expressed that are not otherwise expressed. This fact, combined with the fact that most mutations are recessive may indicate that inbreeding drives evolution. Speciation, a key process in evolution, depends on reproductive barriers, a necessary feature of which is inbreeding."
The mutation process here is driven by inbreeding and keeping the
Re:Someone needs to tag this "Inbreeding".. (Score:4, Informative)
Is that are joke or are you intentionally dense? http://en.wikipedia.org/wiki/Inbreeding [wikipedia.org].
You should be reading this page instead http://en.wikipedia.org/wiki/Asexual_reproduction [wikipedia.org]
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uhh? (Score:2, Interesting)
Forgive me, as I am not a biologist, but...
What does he have to do to "prove" that genetic mutations have occurred beyond:
1) Sequence DNA from original strain
2) Sequence DNA from current strain
3) diff strain1 strain2
Wasn't easy DNA sequencing supposed to be one of the new technological advancements that was changing the world?
Am I missing something here?
Re:uhh? (Score:5, Informative)
Yes. You are missing the fact that this experiment has been running for the last 20+ years. Time is the major factor here. Furthermore, they did a bit more than simply comparing the DNA from the current strain to the original strain. THey kept samples of strains of the bacteria every 500 generations or so and compared them. Even running parallel experiments using these stored strains allowing them to effectively repeat the experiment in order to understand the evolution of the new metabolic pathway allowing for the utilisation of Citrate.
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Not entirely related: These guys [youtube.com] observed the evolution of long-living flies for 20 years (google talk). Although I do have some reservations about their ethics and patents.
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what is the difference between adaptive mutations and random mutations? My understanding of evolutionary theory is that it says evolution is driven first by random mutations, and then the adaptive ones are preserved. So I see a distinction, but the naming here seems a little off-center.
Now I further figure that if the mutations are random, then their adaptiveness is random. Was adaptiveness potential less used up at the beginning of the experiment, thus it was more likely for a random mutation to be adap
Re:uhh? (Score:5, Informative)
A main purpose of the study is to investigate evolution of phenotypes, not just genomes--- i.e. how the functions and capabilities of bacteria change over generations due to evolution. Just showing there was a change in the genetic sequence doesn't do that, since it might be a change that isn't expressed.
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What does he have to do to "prove" that genetic mutations have occurred beyond:
Present it in a way that nobody gets offended. Meaning it should comply with religion so that people can go on living their lies.
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Whoosh!
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Re:uhh? (Score:4, Informative)
That would be one way to go about it, all right. There are a couple of problems though. Current state of the art DNA sequencing runs somewhere in the range of a few tens of thousands per (for humans, perhaps a bit less for something like E Coli). That's a technological advancement, all right, considering when they first started sequencing genomes it was a billion dollar project. It's also not instantaneous. Much faster than it used to be (years or decades) but not instant. Note that the samples he's looking at are ones that have been frozen periodically over the last twenty years. Apparently the price of sequencing genomes has dropped to the point where his lab has the funding to actually do it now.
The diff part isn't trivial either. The genome for E. Coli is around 5 million base pairs long, which doesn't sound like much, if you're just looking for point mutations. The problem is, there are lots of other things that can happen to a genome besides point mutations. Genes can hop around or get copied into the wrong location, which you might count as no mutation, or one mutation, but either way you still have to figure out where it came from. Also, although E. Coli reproduce asexually, they do share genetic information through conjugation, so you get gene shuffling that way. There's also at least some genetic diversity in the colony, meaning you'll be dealing with several different genomes.
Once you've worked all that out, it's not all that interesting just to look at now vs. then. If you wanted to do that you could go dig frozen bacteria out of ice cores or something. The point of this experiment was to be able to watch as the genome changed. So you have to do lots and lots of comparisons, from samples taken at different times (every 500 generations, IIRC, meaning about 80 timepoints). Oh, and there were multiple, isolated populations.
On top of all that, what's really interesting is functional changes. Counting mutations is fine and all, but you really want to know what (if anything) those mutations are doing. The headline event was a mutation that allowed the E Coli to metabolize citrate, for example.
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"Easy" DNA sequencing (e.g. short-read sequencing systems) are still rather expensive, and require a good deal of skill. Even archiving and preparing 40,000 samples would be an enormous challenge. The costs for a "full genome" read of an E.Coli genome (say, 1 or 2 lanes on an Illumina short-read sequencer) would run in the
Yes, that Lenski (Score:5, Interesting)
Re:Yes, that Lenski (Score:4, Informative)
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Another account of the story is at RationalWiki: http://rationalwiki.com/wiki/Lenski_affair [rationalwiki.com]
RationalWiki is a site that exists to poke fun at Conservapedia and the anti-science movement. (I particularly like its WIGO page, "What Is Going On At CP? [rationalwiki.com]".) Conservapedia forbids any mention of RationalWiki, going so far as to ban members who make oblique references to it. In fact, the part of Lenski's letter that was censored on Conservapedia as "Ed.: citation omitted due to spam filter" was, originally, a referenc
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http://en.wikipedia.org/wiki/Conservapedia [wikipedia.org]
Evolutive pressure? (Score:2)
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I'm a signature virus. Please copy me to your signature so I can replicate.
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There is a step from "DNA mutation" to "Evolution", and that is adaptation to the medium. Did the mutations change the fenotype (the external aspect/behaviour) to something more adapted? Were set certains goals (for example, putting them in a medium less than ideal for the original strain, but to which its survivors have adapted) or the surviving changes did not affect at all at the species?
I think what you're trying to ask is: "Was the selective pressure determined to be in response to stimuli versus a random occurance?"
The authors cover the difference between neutral drift and selective mutations which increase fitness throughout the paper.
Specifically in answer to your question, though, is the following from the expanded methods & materials:
"We performed Luria–Delbrück fluctuation tests33 to confirm that the Ara-1 population evolved an elevated mutation rate. Bacteria were re
A very interesting thought, (Score:3, Interesting)
would be, if you could say, that there are parallels to human evolution.
At first, E. coli adapted to the environment. But when there was nothing to adapt to, because nothing changed anymore, mutation almost switched to a different "mode", where random changes got bigger. My guess: In the battle to stand out of the crowd and become dominant.
Now the parallel would be, that humanity also now dominates the planet, and very little can eradicate whole humanity. So for all of humanity, the risk is very close to zero. Which could mean that now, we also rather fight ourselves, in the battle to stand out and become dominant.
I mean after all, even with "global peace" (something that will never happen), "everyone is equal", and all that stuff, it's still an evolutionary game, where those with even the slightest advantages, will in the end "win".
Just that now we are perhaps evolving in a "mode" where it's not for the best of whole humanity anymore, because that became insignificant.
My guess here, is that this is, how diversification into different species (at the very beginning) starts to happen...
Not Convincing to Public (Score:3, Interesting)
This is not "dramatic" enough to convince the general public of the power of evolution. A more interesting experiment would involve the Mud-skipper fish; a fish that can hop on land for short durations but has no close relationships to amphibians or lung-fish, being the "fan ray" fin type.
I'd like to see an attempt to breed them via nation-wide contests to evolve the fish into a more efficient walker or hopper. Races could be held at high-schools and colleges, and the winners would be bread with other regional winners to produce a more land-friendly next generation. The gradual process could be observed by all.
I discarded the chimp version of this after watching Planet of the Apes :-)
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Mmmm, breaded mudskipper.
I thought this sort of thing... (Score:4, Interesting)
took millions of years. Nobody with eyeballs doubts that things change over time. What we're finding out finally is just how long it actually takes for things to change.
Evolution or just surving? (Score:2, Insightful)
Everyone assumes that the E. coli bacteria "evolved" its way into better dealing with adverse conditions (citric acid, etc.). Not true - the ones who HAPPENED to be able to withstand and metabolyze citric acid DIDNT DIE - the survivors didn't evolve to metabolize it, they already could. Animals don't genetically adapt to change - the ones already predisposed to tolerate the change survive.
Re:Evolution or just surving? (Score:5, Insightful)
Congratulations! You've just described the process of evolution.
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On this particular subject, and I know this is unrealistic on slashdot, it would be good to read the article. The techniques used in this study were brilliant, they are specifically designed to investigate the criticisms that are usually leveled on studies of evolution and they do so beautifully. I'll try for a quick explanation of why your criticism is invalid.
First, how the experiment worked. They put E. Coli. into dishes with a growth medium of glucose and other nutrients with glucose as the limiting
Random change is ... random? (Score:2)
From the summary,
"...genomic evolution was nearly constant for 20,000 generations. Such clock-like regularity is usually viewed as the signature of neutral evolution, but several lines of evidence indicate that almost all of these mutations were beneficial. This same population later evolved an elevated mutation rate and accumulated hundreds of additional mutations dominated by a neutral signature. Thus, the coupling between genomic and adaptive evolution is complex and can be counterintuitive even in a con
Nobel? (Score:3, Insightful)
No Nobel (Score:5, Funny)
Sorry, they're saving the next Nobel Prize in Medicine for Obama...
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Not yet.
The creationists will blindly and steadfastly cling to their mysticism-based pseudoscience until two chimps mate and produce a homo sapiens offspring.
Which of course is not how evolution works.
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> When he turns it into a buffalo, he'll have something.
Wow, ignorant and condescending. Less bible studies and more high school biology for you, I think.
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the absence of an external population with which to mediate the process
What difference does that make? Populations are isolated all the time and is in fact a common mechanism of evolution. See Darwin's finches.
in the wild, would the group go through a smaller or greater number of mutations?
Barring mutagens, they would have the same number of mutation. Selection pressures for those mutations would be of greater importance.
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While I don't believe in creation, mutations occuring in 40,000 generations (one mutation every 63 generations) of inbred bateria is hardly proof of evolution.
Well I understand your point. But then what would you suggest is more likely?
Re:hmmm (Score:5, Informative)
ALL mutations are random. If they are advantageous, great, than it is likely that they will be passed along.
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If more harmful mutations are being passed along than favorable, then either you're misclassifying mutations are harmful or your population is, in fact, evolving to a dead end that may result in population death.
If it doesn't, then what's the basis for the "harmful" classification?
Re:hmmm (Score:4, Informative)
Evolution is a two-step process - the first part is the production of mutations, which is a random process (and, given how finely balanced organisms are, the majority of these random events will probably be negative, on balance). The second part is selection - if there is genuine competition between these strains, then the beneficial mutations will be selected, so the fact that they are relatively rare will have little effect on their eventual domination of the population.
Re:hmmm (Score:5, Informative)
This also allowed the total population in that group to explode (there's now more food in total, glucose + citrate).
Another cool thing is that this smashes the "Irreducible Complexity" argument. The ability to metabolise citrate is developed by two separate mutations, which, on their own achieve nothing. Some of the populations developed the first mutation and some developed the second one, but none of them had previously developed both. This shows that the "preliminary" mutations were not harmful to the bacteria, so they just "hung around" until one of them was lucky enough to get the second mutation too.
Anyway, look up Lenski's work, I'm sure his papers (and those of his students/colleagues) are better at explaining it all than me...
Re:hmmm (Score:4, Funny)
*kisses karma goodbye*
My issue in general here (yes, I am a creationist...I'm a delusional moron, I know) is that while 40,000 generations of E. Coli did show some form of usable mutation, it doesn't account for many other inconsistencies with evolution as the be-all and end-all for how we got where we were. My biggest issue is that, to my knowledge, there has never been a documented observance of life coming from non-life.
But the one more relevant to your point about this disproving the concept of irreducible complexity has problems of its own. Yes, there was indeed an evolution of the bacteria being able to process citrate. However, that's a smaller step than, say, if E. Coli bacteria started to be able to perform photosynthesis, or vice versa. There are other extremely wide gaps (asexual reproduction to sexual reproduction, live birth vs. egg laying, visual and audible processing, etc. etc.) that are still a challenge for gradual, incremental evolution to explain. The most immediately memorable example of this for me is the bombardier beetle. The system it's got in place to ward off predators relies on a series of chemicals and an expulsion system that incremental evolution can't account for. If any of those pieces evolved improperly, there would be no fossil record because the beetle would have a Fourth-of-July special internally before it ever got to reproduce.
I'm not one of those crazed creationists who believe that everything we see today is exactly how God created it, but full-blown, evolved-over-billions-of-years-from-a-singularity-filled-with-energy evolution is still a challenge for me to accept. If that makes me $DEROGATORY_COMMENT, well, I already said goodbye to my karma points.
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> The study shows that the populations are becoming more damaged over time, rather than stronger.
I think that the study shows that when there is no competition, mutations become more likely.
Now imagine this: An island, no-one lives there, except rabbits. No competition, except from other members of the same population. Now, based on evolution theory, those rabbits that can eat most of the grass, will succeed. But even more successful would be a "rabbit" which would eat something else, what other rabbits
Re:hmmm (Score:5, Insightful)
I don't think you shouldn't participate in any discussions about evolution until you acquire some elementary biology knowledge.
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Err. No.
Any given mutation would have the same chance of occurring in the wild. It may be more likely that said mutations would result in their carriers being outcompeted in the wild, but that does not in any way shape or form indicate that such mutations would not appear (and potentially persist for a period of time) in the wild.
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Nonsense. Evolution is nothing more than organisms adapting genetically to their environment. These bacteria are doing exactly that.
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Indeed evolution is. However, the individual I was quoting suggested that anyone was an idiot who didn't fully believe in evolution purely on the basis of a controlled group of bacteria, forced to undergo mutation through lack of natural competition, in a controlled environment. I'm not arguing against evolution or the results of the experiment, I'm arguing against parent who couldn't even be bothered to read far enough to find out what the mutations were or which what percentage of fixated mutations were b
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That isn't quite true. The individual that you responded to did not suggest that our evidence for evolution was solely this experiment. That would be extraordinarily ignorant. We have in fact enough evidence of evolution that the books written on the subject alone would crush any creationist standing underneath their shear mass.
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Huh?
Genetic mutations are by definition evolution.
Maybe what you meant was that it's not proof of what creationists like to term "macro evolution" (a scientifically meaningless term which I gather roughly means evolution of new species).
The only functionally useful definition of new species is ability to interbreed which make me wonder how you are guageing that in a species (ecoli) that predominantly reproduces asexually!
I wonder if the starting and ending strains were unable to reproduce by conjugation you
Re:hmmm (Score:5, Insightful)
Re:hmmm (Score:5, Informative)
"Look, I believe in evolution, but never has there been found a parent species to something alive today. In other words, scientists can not point at any two distinct species, living or extinct, plant or animal, and say that this species evolved directly from that one."
Of course not. That's kind of like pointing to two leaves on a tree and saying one leaf came from the other. It doesn't work that way. They are both on the terminations of the branches, and the node where they branched into two is in the past. Ordinarily, the common ancestor is long dead. The nice thing with these E. coli is that the researchers kept a portion of the ancestral population intact, and the specimens are clones, so while not the actual ancestor of the lineage that kept going, they are genetically identical.
There are plenty of fossils that are close to branch points, and as more fossils are found there are still plenty of gaps left, as there always will be, but the changes necessary to span those gaps get smaller and smaller as the sampling improves. For example, Anchiornis [wikipedia.org] was just discovered in the last couple of years, and a new specimen described a few weeks ago. Dinosaur? Bird? It's rather arbitrary to decide. It's either a wing-clawed, long-tailed, toothed bird like no modern bird, or it is a flight-feathered, gliding dinosaur. As if they were the leaves on a tree, birds and reptiles look distinct now, but follow the branches back far enough and they get mighty blurred together. This is hardly an isolated example.
There are fish that look so tetrapod-like that when the skull was initially found separately they thought it was a tetrapod [devoniantimes.org]. Then workers found the rest of the body and realized it was a fish. There are other tetrapod-like fish, such as Tiktaalik [uchicago.edu]. But go back 100 years and these species weren't known at all.
I really don't know what more skeptics are expecting. Perfection? It won't happen. It's not like we'll ever have every twig on the tree. Good fossils are rare. But the statistical pattern with increased sampling is quite robust.
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Of course not. That's kind of like pointing to two leaves on a tree and saying one leaf came from the other. It doesn't work that way. They are both on the terminations of the branches, and the node where they branched into two is in the past. Ordinarily, the common ancestor is long dead.
No, the common ancestor is always extinct. Why?
Mammals formed in the Tertiary period, about 65 million years ago. Every mammal alive today evolved from these rodents, possibly, a single rodent. That means that every elephant alive today, evolved from a small rat-like creature 65 million years ago. We should be able to track a single line from any elephant back to a single rodent. Each generation having only two parents. There are a LOT of changes that had to happen between this little rodent and your
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To use an analogy, let's compare the evidence to a murder trial:
Wait, can you put that in a filesystem developer analogy?
Re:hmmm (Score:5, Insightful)
Explain crocodiles. According to the fossil record they have hardly changed from their ancestors millions of years ago. But they *have* changed. And we don't "only find the dead end". There is no dead end if there are descendants. What you're forgetting is that fossilisation only happens in relatively rare circumstances, so the vast majority of the record is not preserved at all. That unfortunately is where the step by step evolution would be easily recognised. But you can still fill in the gaps with insight and close examination. After all, the current generation came from somewhere, and it's pretty unlikely it started from scratch as is.
Regarding crocodiles, the current species get to between 20 and 30 feet in length. Crocs in the Cretaceous period were around 40 feet in length. But back then they were dealing with prey much larger than is available today. Overall, most species on earth are smaller than their ancestors, except of course humans, who have no real predators and are able to take advantage of a wider range of foods.
We have played our part in the destruction of the chain of evidence too. If you buy fish, you may have seen a halibut on the counter. Maybe it's a couple of feet long, probably less. But specimens have been caught that are 7.5 feet long and weigh over 621 pounds. They only get that big through long life, and these days we are catching them before they ever get that big. Future paleontologists will wonder why the "giant halibut" died out relatively suddenly, but there will be no missing link fossils because we ate them.
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You know, it only took me 10 seconds to google for an example, you could have tried a bit harder. "speciation observed in salamanders":
http://www.santarosa.edu/lifesciences2/ensatina2.htm
A species observed to lose reproductive compatibility between populations separated by geographic barriers.
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Not true. You are posing the missing link myth. There are in fact good lines of fossils showing evolutionary trends in species for many different species in the fossil record.
While no we do not and never will have a direct individual by individual line of fossils simply because most creatures that lived on this earth were eaten, rotted and NOT fossilized. Fossilization also did not occur uniformly through all species or stages of evolution, it was collection of many random processes, and thus one would e
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They already demonstrated the E.Coli bacterium evolving the ability to metabolize citric acid... that makes it a new kid of bacterium (the inability of E.Coli to metabolize citric acid is one of its defining characteristics).
And the color white was a "defining characteristic" of swans until they found a black one.
And the black swan (Cygnus atratus) is, in fact, a separate species. So even by your own argument-by-analogy, you've agreed that the new bacteria should also be considered a new species, and thus evolution has been observed to occur.
Look, I believe in evolution, but never has there been found a parent species to something alive today.
My grandparents have all passed away, but I'm pretty sure I'm still related to my cousins.
In other words, scientists can not point at any two distinct species, living or extinct, plant or animal, and say that this species evolved directly from that one.
We've had plenty of genetic evidence from preserved material to say exactly that. But the big news about Lenski's experiment is that not only do we have living examples of a species which
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No, this is not true. In plants, polyploidy can lead to the production of a new species, reproductively isolated from the parent species, and quite often ecologically distinct as well. This happens in a single generation, and in some cases you m
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what you are asking for is exactly what this studied proved.
No. What this study provided are variations of E-coli.
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No such thing? Are you retarded or willfully ignorant: http://www.talkorigins.org/faqs/macroevolution.html
The only difference between macro- and micro- evolution is the time-line.
Each little step/mutation is EVOLUTION, to split the changes into "micro" and "macro" is to diminish the meaning.
You could have dogs evolve into whales, but if you looked at each mutation individually, you could dismiss it as "micro-evolution".
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No such thing? Are you retarded or willfully ignorant: http://www.talkorigins.org/faqs/macroevolution.html [talkorigins.org]
The only difference between macro- and micro- evolution is the time-line.
The way I heard, the difference is one is rearranging what's already there (allele frequencies changing), and the other is actual new stuff (like these particular e coli being able to eat citric acid).
From looking at that link it looks like this actually is one of the ways those terms are really used, although they're quite fuzzy and don't always mean the same thing.
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You missed the evolution of the ability to metabolize citric acid.
There's no luck involved here- there's just a mindbogglingly high number of mutations and tests of those mutations over the course of history. You say "even over the lifetime of the universe", but it's unclear to me that you really understand just how large a number of generations there have been even since the rise of life on Earth, let alone the entire span of the universe. That's a lot of individuals, a lot of generations, a *lot* of mutat
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I am curious to know that why would mutate those germs in a short period of time, in a potentially unchanged lab environment? What are they adapting to by evolutionary mutation?
There's two reasons.
First it is a somewhat different environment than they evolved in. Particularly if this was the same bacteria as the previous article I think they were also exposed to a new nutrient (citrate?) that they learned to metabolize. This trait evolving could be the reason that their mutation rate jumped up as they adapted to their new condition.
Second, even if there wasn't any adaptive pressure there's still evolutionary drift as unimportant changes show up and propagate through sheer chance.
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They would be competing against each other for the existing resources (petri dish space, the nutrients available, the warmest darkest place of the container).
Each bacterium will have random transcription errors. If these are fatal, the descendant won't reproduce. They have the trade-off between reproducing slowly with fewer mutations but being outbred, or reproducing quickly with more mutations and less chance of being outbred. So it looks like breeding quickly and risking genetic mutations is the better op
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In the first stage of evolution (under 20,000 generations) a random mutation had a higher chance of being fatal. The E.Coli they used were already pretty specialized for general survival. They probably didn't fish this E.Coli out of hot springs or out of glacial ice. They then put the bacteria into an environment that they probably haven't encountered before, with no way out. A culling happens, where the ones that cannot handle the citric acid die off. So now we have a batch of reproducing survivors th
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I haven't read the Nature article (no free access from home), but my guess is that the "adaptive" mutations are indicative of a brittle genome where most mutations result in a drastic decrease in fitness, such that the individual mutations aren't propagated very well and thus aren't detectable amid the large population of bacteria.
In the latter case, it sounds as though a particular portion of the genome was rendered inert or unimportant, such as by a modification of the metabolic pathways to eliminate a po
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Perhaps you should define as to what you think evolution is, before you say you don't see any.
Re:Mutation does not equal Evolution (Score:4, Informative)
The standard method of identification of bacterial species is to determine what compounds they can eat. E. coli is defined as not being able to eat citrate. They evolved something from E. coli which can eat citrate. The new bacteria is not E. coli by the standard method of identification.
But I guess you're right... it's still just some random nigh-invisible animalcule that nobody really cares about. I mean it didn't turn into a dolphin, did it?
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Yeah, I agree. I've been following physics lately and it's weird how the "scientists" only test micro-gravity -- it's like they are trying avoid building planet size objects for their tests even though it's clearly required before their theory could be taken seriously. "Theory of Gravity", hah!