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Ever Evolving E. coli

Scientists show that bacteria continue to become more fit, even over tens of thousands of generations.

By | November 17, 2013

WIKIMEDIA, BRIAN BAER AND NEERJA HAJELASince 1988, Michigan State University’s Richard Lenski has led the Escherichia coli Long-term Experimental Evolution Project (LTEE)—12 flasks of bacteria that have been evolving in the lab for more than 58,000 generations. In the latest report from the project, Lenski and colleagues have shown that peak fitness—the point in an organism’s evolution when it is maximally adapted to its environment—does not seem to have an upper limit. Their work was published in Science last week (November 14).

“What this result says is that there are even more ways of adapting to environments than we imagined,” John Thompson of the University of California, Santa Cruz, told New Scientist.

Lenski’s team thawed E. coli taken from the LTEE at 41 different time points during the past 25 years and cultured the samples from different generations together in varied combinations with the most current generations. They evaluated fitness based on how fast the bacteria grew and found that even between 40,000 and 50,000 generations, there was a 3 percent increase in mean fitness. The scientists generated a model, which predicted that even if the experiment continued for 2.5 billion years, there would not be an upper bound to fitness.

“There is always tinkering to do, and you can always improve things a little bit,” Joachim Krug of University of Cologne in Germany told New Scientist

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Avatar of: mchrqrd

mchrqrd

Posts: 1

November 18, 2013

This is not a very significant evolutionary event. These eColi remain eColi even after 58,000 generations. Why no new bacterial sophistication? The bacteriophages and reproduction by binary fission make their adaption models completely useless models for evolutionary models in the animal kingdom. In fact, the 58,000 generations of careful observation have not produced a single new species, no multicellular structures, no increased sophistication, and maintain the complete amorphous structure that keeps them from becoming anything else. Bacterial evolutions do demonstrate DNA changes, unlike any of the finch beak gene pool isolations or other minor changes that some scientist have touted as "evolutionary proof". Fact is there are no instinctions, only extinctions. Instinctions isn't even a word. In the written history of man, no species has ever evolved into a genetically different species. There have only been gene pool isolations, like ring species and dog breeds, but no signficiant morphological DNA changes. DNA is too sophisticated and too complex with detailed intercoding to ever change by random mutation. Evolution is the largest farce of the 20th century. It's sure to be refuted in the coming years, if not months.

Avatar of: James V. Kohl

James V. Kohl

Posts: 151

November 18, 2013

In the "Science" article, the authors claim to "...minimize complications and thus illuminate the fundamental dynamics of adaptation by natural selection in asexual populations."

Excerpt: "The medium has one limiting resource and supports low population densities (for bacteria) to minimize the potential for crossfeeding on, or inhibition by, secreted byproducts."

My comment: They eliminated natural selection for nutrients via the medium used to grow the organisms. This limits the metabolism of  nutrients to species-specific secreted byproducts called pheromones that control the physiology of reproduction. Thus, the conserved molecular mechanisms of  nutrient-dependent pheromone-controlled adaptive evolution are eliminated and results are reported in terms of mutations.

This experiment was designed before researchers knew anything about molecular epigenetics. Nothing is illuminated by first eliminating variables that include the epigenetic 'landscape,' which becomes the physical landscape of DNA in the organized genomes of species from microbes to man that adapt to their environment.

I am surprised at attempts to explain the evolution of organismal complexity in the context of mutation-driven evolution, when no experimental evidence from model organisms in their natural or typical environments supports that idea. Instead, all experimental evidence supports nutrient-dependent pheromone-controlled adaptive evolution.   

Avatar of: Ferit

Ferit

Posts: 1

Replied to a comment from mchrqrd made on November 18, 2013

November 18, 2013

do you realize how small 25 years is compared to a few billion, or million years? and imagine the environmental variation bacteria experience in those years. this experiment shows they'll keep on varying. i don't think you creationists do anything but deceive.

Avatar of: JohnnyBxo

JohnnyBxo

Posts: 3

Replied to a comment from mchrqrd made on November 18, 2013

November 19, 2013

Wow, months? I'm sorry but that will never happen. 25 years is really no time at all and I was surprised to see even a 3% increase in mean fitness over such a short time!


We just need to keep this experiment going. It's incredibly interesting!

Avatar of: rhollis

rhollis

Posts: 1

Replied to a comment from mchrqrd made on November 18, 2013

November 19, 2013

You are not even close to being right.

Like so many woefully uninformed Creationists, you seem to believe that evolution states that one species should give rise to a non-species: that a cat should give rise to a non-cat, a bird give rise to a non-bird, or a bacterium give rise to a non-bacterium. That is a fallacious concept.

The theory of evolution ACTUALLY predicts speciation: that a cat will give rise to differing species of cats, a bird will give rise to differing species of birds, and a bacterium will give rise to differing species of bacteria. And that is exactly what this study demonstrates - twelve now-vastly different strains of bacteria all originating from one strain. This is evolution observed in action.

What's more, one of these strains has evolved an entirely new adaptation - the ability to digest citrate. This is an entirely new and complex ability (that is, an INCREASE in complexity) resulting from nothing but random mutation and natural selection. And the icing on the cake is that this is not an ability that rose from a single mutation - it arose from two individually neutral mutations working in concert. In short, this is a so-called 'irreducibly complex' system appearing right before our eyes; something our Creationist friends assured us was absolutely impossible.

And as for DNA being "too sophisticated and too complex with detailed intercoding to ever change by random mutation", are you seriously trying to suggest that mutations to DNA simply never happen? That there is no such thing as a genetic mutation? Are you aware that the average human being has 60 mutations to their genetic code? Or are you trying to suggest that no mutation could ever possibly be beneficial? Because if you are not saying either of these things then you simply aren't making any sense. Random mutation alone does not drive evolution - natural selection does.

Avatar of: Intron

Intron

Posts: 4

Replied to a comment from mchrqrd made on November 18, 2013

November 19, 2013

58,000 generations is merely 25 years of the same progeny and 25 years is nothing in evolutionary time. If it only takes 25 years for some bacteria to evove into multicellular organisms, I'd surprised not to see the entire human race evolves to be much smarter while the creationists lag behind...

In the history of man, dog was domesticated from wolves, gold fish and Koi carp was developed from wild carp. What more morphological changes do you want? Evolution in a nut shell is in fact the change of gene frequencies in the population, nothing more special. There is no clear boundaries between different species. The old definitions of species are largely outdated and inaccurate. That being sad, still, every species is still geneticially different. People should get rid of the mentality of black-and-whitism and the false dichotomy, do some proper research, before making any bold claims to discredit any scientific theory.

Avatar of: SeanW

SeanW

Posts: 5

November 19, 2013

Hi Everyone:

I agree that 25 human years is not a long time. However, before blasting creationists I urge you to look at the following comparison:

-To reach 58,000 generations of the human species, it would take approximately 2,331,600 years.* Therefore, if the same changes in E. Coli holds true to humans that means we took, or will take, 2.33 million years to become 3% better. (Basically we haven't come that far as humans if this holds true.)

Now this was a controlled experiment which automatically has its own benefits and inhibitions. There is a greater possibility of outside factors in the actual environment in which we live. For humans, these factors could have been the discovery of crops and crop rotation. The discovery of fire and metal tools. These events may have caused dramatic adaptions by which we improved ourselves. 

The fact of the matter is that Evolution is the adaption of genetics over time in which those traits build a better plant, animal, bacteria, etc. My personal belief of creationism is that God, or whichever name of deity you choose to believe or even not believe, guided the evolution of man.

If that is offensive or incorrect to you, then I urge you to take another look at this experiment. A being, Dr. Lenski and staff, with higher intelligence has created an environment in which bacteria grow and evolve.

Who is to say that God cannot be a being of higher intelligence that, using the natural laws of the universe, created Earth and caused the evolution of man? To say it is impossible for that to occur is to deny the evidence this study presents.

In the end I know that compared to all the knowledge contained in the universe, I know pretty much next to nothing.

*This was calculated using the maximum life expectancy from Life Expectancy Over Time from Wikipedia (http://en.wikipedia.org/wiki/Life_expectancy). I do realize that the numbers may be off plus/minus 10-20 years, but over the course of 2.3 million years I think that it is irrelevant.

Avatar of: Europe

Europe

Posts: 1

November 19, 2013

Really guys, just from reading your comments I know you that are just average conservative americans who still read the same book from 2000 years ago. Scientists are called out-of-date after missing even 5 years of research books.

Don't get me wrong, I'm also a christian like you. But I take the bible as what it is: A book. Written by humans. And screw the first perverted half of it, Christ is in the second part. And he did a real good job spreading his philosophy of peace and love. But he was only playing a god because the people wanted him to be. It was the only way to make them follow his teachings. Because people handled the smart people the way you do today: Calling them crazy and heretics and not legitimated to tell them anything about life to make it better.

So forget the stupid Genesis, it was just a story! Welcome to the 21st century: Evolution is a fact (since early 18th century btw). This experiment is actually another proof of evolution, or either the bacteria wouldn't have changed at all! And U.S. people are the only ones in the world to stubbornly lie to themselves about it and even invent a term like "Evolutionists" for the rest of the sane world. Yes, 25 years are nothing for a human being, THAT'S WHY THE EXPERIMENT WAS MADE WITH BACTERIA AND NOT HUMANS! So 1 human generation is 58 000 generations for Bacteria. OF COURSE scientists would love to inspect the same experiment with humans, but the problem is that scientists would have to live 1 450 000 years to do that. And stupid capitalism joe wouldn't pay any research, no matter how brilliant, if he can't see the fruits of his "investments".

Please grow up already and stop believing in ghost storys. Follow Christs teachings simply because they are the right thing to do, not because he made everyone believe in some magic tricks. His teachings of love, respect, modesty and sharing are still the right way of living. (That's why the buddhists like those ethics, too. Without having a god)

And now please stop writing ridiculously stupid comments.

Avatar of: jezbeach

jezbeach

Posts: 1

Replied to a comment from mchrqrd made on November 18, 2013

November 19, 2013

> no increased sophistication

You're completely factually incorrect, in 2008 one population in this experiment (Ara-3) evolved the ability to grow on citrate, something that wild e-coli cannot do.

This is a clear case of increase in complexity driven by evolution.

Of course if you expect a single-celled bacteria to evolve into a multi-celled organism in just 25 years (it took life on earth 2.5 billion years to do that) then you clearly have no understanding of evolution.

Avatar of: James47

James47

Posts: 1

Replied to a comment from SeanW made on November 19, 2013

November 19, 2013

There are a few very important factors that your comment does not take into account.

First: The experiment was done on bacteria contained in 12 flasks.....compare the number of bacteria living in those 12 flasks to all the single celled organisms living on the entire planet and you may realize that there are many more possibilities for traits to evolve than you realized.


Second: The flasks were likely stored in a controlled consistant environment as opposed to the to ever changing environment on earth that undoubtable would have exposed organisms to many different events and conditions that would push evolution in various directions, for example if the ecoli were to be split into two groups and one put in a hot and humid environment and the other in a cold arid environment and those two populations would likely yield very different adaptations


Third : Human DNA is much more complex than e.coli DNA and is more suseptable to mutation

 

Fourth: Humans reproduce sexually as opposed to asexually, again this allows for the selective mating process to drive evolution in certain directions

Avatar of: Clem

Clem

Posts: 1

November 19, 2013

Not sure why the emphasis in these comments about calendar time vs. generations of progeny.  Bacterial reproduction is exponentially fast compared with animal reproduction, so we should expect to see more rapid evolutionary results in shorter calendar time with bacteria due to their extremely short generation time.  Obviously, E. coli was chosen because it is capable of producing countless generations within the lifetime of the researcher, so it's a convenient subject for that reason rather than for its likelihood to produce significant evolutionary advances.  Not the greatest study one could design.

Replied to a comment from SeanW made on November 19, 2013

November 19, 2013

Sean W, Richard Dawkins addresses this in "The God Delusion". I challenge you to read it. 

Avatar of: ekimdwod

ekimdwod

Posts: 1

November 19, 2013

Please don't react to the moronic creationists you will only get frustrated. Time will remove them from the population. Be patient

Avatar of: Max wyght

Max wyght

Posts: 1

Replied to a comment from SeanW made on November 19, 2013

November 20, 2013

Humans are 0.2% different from chimps.

Basically, that's a 1/15th variation in comparison to the bacterium.

Avatar of: SeanW

SeanW

Posts: 5

Replied to a comment from James47 made on November 19, 2013

November 20, 2013

James47,

I felt I acknowledged your first, second and fourth points in my statement:

Now this was a controlled experiment which automatically has its own benefits and inhibitions. There is a greater possibility of outside factors in the actual environment in which we live. For humans, these factors could have been the discovery of crops and crop rotation. The discovery of fire and metal tools. These events may have caused dramatic adaptions by which we improved ourselves.

As for your third point, admittedly there are millions upon millions of factors that can affect the evolution of a single-celled organism.Environmental is perhaps the largest along with interactions with other organisms. (Interactions including killing, eating, domesticating, etc) These factors would probably be multiplied exponentially in a multi-celled organism. Many traits change and evolve throughout each generation of an organism. Examples in humans include red hair, black skin, larger skull structure and millions of others are examples of genetic mutations.

Although I do maintain if humans only changed 3% in 2.3 million years, we haven't advanced very far. I believe it is extremely unlikely that we have only changed 3%.

Thank you for expanding on my statement. I feel that by posting your points we all benefit from the educational process by expanding our minds.

Avatar of: SeanW

SeanW

Posts: 5

Replied to a comment from Clem made on November 19, 2013

November 20, 2013

Clem,

You are absolutely correct. Bacteria, viruses, and other single or simple celled organisms multiply exponentially faster.

For my part, I use calendar time as a way to simplify the discussion. This is mainly because I'm an accountant, not a microbiologist.

 

Avatar of: SeanW

SeanW

Posts: 5

Replied to a comment from Max wyght made on November 20, 2013

November 20, 2013

Max,

The American Museum of Natural History states "humans and chimps share a surprising 98.8 percent of their DNA." If I do my math correctly, it's a 1.2% difference.

Regardless it's absolutely amazing what a small difference can make.

-http://www.amnh.org/exhibitions/past-exhibitions/human-origins/understanding-our-past/dna-comparing-humans-and-chimps

Avatar of: SeanW

SeanW

Posts: 5

Replied to a comment from Richard Dawkins for prez made on November 19, 2013

November 20, 2013

Richard Dawkins for prez,

I read the wikipedia article about it. In the future, I might read the actual book. If you're willing to buy and ship it to me I promise I will put it on my bookself and hopefully read it sooner rather than later. Unfortunately, I currently do not have time to do so. (Pesky school work and exams!)

From what I read of his biographical wikipedia article, in which it states:

Dawkins is a prominent critic of creationism (the religious belief that humanitylife, and the universe were created by a deity without recourse to evolution). He has described the Young Earth creationist view that the Earth is only a few thousand years old as "a preposterous, mind-shrinking falsehood."

As I stated before, I believe that an intelligent being can create life and use a process of evolution to change and grow that life. The Earth is obviously older than 4,000 years old, but there is also a lot of information missing from the Holy Bible. It is not a perfect book. Indeed, it was only assembled into the 1 distinct book as we now know it in the 4th to 5th century A.D.

I believe Intelligent design is not inherently complex if the design is based on the basic principles upon which the universe operates. We merely have to learn and practice those principles and they become easier and rather simple to us. For example, I bet you find basic arithmetic  and spelling easier to do now than when you first started learning it.

In the end the pursuit of science is imperfect and fails to explain everything in our natural world. It will continue to do so until we have learned it all. It which case we will become omniscient, which will be a very, very long time from now. Besides, statistical improbabilities still happen and will continue to do so.

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

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

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

Side note: Richard Dawkins would be unable to become president of the USA as he is, at the very least, not a natural born citizen.

Avatar of: SSluman

SSluman

Posts: 1

Replied to a comment from mchrqrd made on November 18, 2013

November 24, 2013

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