Evolution through 21-year E. coli experiment

Oh, ok, we're on the same page now.

'Natural selection' is a common phrase for a particular phenomenon that inevitably emerges from population dynamics. A kitsch phrase such as 'natural, not supernatural, selection' is quaint, but completely misses the point. We know natural selection works, we've seen it in action, we've predicted its moves, and it's theoretically sound.

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"I am a scientist... when I find evidence that my theories are wrong, it is as exciting as if the evidence proved them right."

We call them random events, not chance events - rather like rain falling on the pavement (sidewalk), you know a drop is going to fall, but you can't tell exactly when and where. Continuous random genetic variation followed by some form of selection is the only way something can adapt to unknown, unforeseeable events, such as a new or changed metabolite appearing in the environment like citrate or nylon. It's a type of trial and error approach, much like the way a blind man points his stick in random directions until he finds a path forwards.

Concerning interpretation of the facts: before DNA and genetics were properly understood, biologists had made classifications of living organisms and had constructed the Tree of Life. This is a representation of relationships between species and lineages and takes the form of nested hierarchies. The Tree of Life was constructed before Darwin's publication of The Origin of Species and has since been seen as the consequences of descent with modification and speciation. More recently, the genetic relatedness of organisms has been compared to the biological classifications and has been found to generally correspond - those organisms that are close on the tree have less genetic variation in their genes compared to those that are further apart on the tree. So what you call "random distribution" from "a single observation" is not true. We have countless thousand observations that demonstrate, by and large, that mutations occur at a steady rate and randomly. Chaos has nothing to do with it.

I can't see how you can have an inbuilt adaptatory system that has the ability to anticipate future conditions. It would need such a huge library of metabolic possibilities its genome would be massively overloaded - and this is not what we observe.

These experiments are a brilliant way to keep graduate students busy. It's probably mind-numbing work to culture and plate all of these variants. Perfect work for graduate students that have little training and need an ongoing project to move right into.

I don't know for sure, but I have a strong suspicion that these experiments were started with graduate students in mind.

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“Because they know not the forces of nature, and in order that they may have comrades in their ignorance, they suffer not that others should search out anything, and would have us believe like rustics and ask no reason...But we ask in all things a reason must be sought.” --William of Conches (c. 1090 – after 1154)

Just for reference, the classic experiments that demonstrate the randomness of mutation are:

Luria-Delbrück experiment - Wikipedia, the free encyclopedia

http://aem.asm.org/cgi/reprint/10/4/345.pdf

Both experiments demonstrate that beneficial mutations arise prior to selection meaning that mutations occur independently of need.

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“Because they know not the forces of nature, and in order that they may have comrades in their ignorance, they suffer not that others should search out anything, and would have us believe like rustics and ask no reason...But we ask in all things a reason must be sought.” --William of Conches (c. 1090 – after 1154)

Are you serious? I bet it was fascinating when they noticed the turbosity and got to determine that it was actually the E. coli utilizing citrate! Can you imagine how exciting that must be?!

I think no matter how exciting it is (and believe me, reading that report was exciting) it's got to be balanced out a little by the mountains of work that would inevitably follow a breakthrough like that.

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"When work seems overwhelming, remember that you are going to die"
Strangely enough this motivates me.

mmm, probably true.

This was a good thread to read. Take a lesson and notice who didn't make any posts in it. That should tell you why this subforum went downhill so fast. Stop letting certain people thread-jack everything and it might be respectable once again.

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Judging by the stats, the top five posters are:

laconicstudent 15
Wiccan_Child 11
Mike Elphick 10
random325nicaea 9
Jazmyn 4

What are you insinuating?!

__________________
"I am a scientist... when I find evidence that my theories are wrong, it is as exciting as if the evidence proved them right."