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Biotech Science

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."
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Observing Evolution Over 40,000 Generations

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  • uhh? (Score:2, Interesting)

    by blhack ( 921171 ) on Sunday October 18, 2009 @05:16PM (#29787013)

    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?

  • Yes, that Lenski (Score:5, Interesting)

    by JoshuaZ ( 1134087 ) on Sunday October 18, 2009 @05:46PM (#29787277) Homepage
    This is the same Richard Lenski whom Conservapedia (the right-wing Christian alternative to Wikipedia because Wikipedia is evil) repeatedly attacked. Apparently his work is such strong evidence of evolution, that Conservapedia's response was to more or less accuse him of faking the data. See [].
  • by Hurricane78 ( 562437 ) <deleted.slashdot@org> on Sunday October 18, 2009 @06:19PM (#29787539)

    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...

  • by Tablizer ( 95088 ) on Sunday October 18, 2009 @06:50PM (#29787749) Journal

    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 :-)

  • by KalvinB ( 205500 ) on Sunday October 18, 2009 @07:22PM (#29787937) Homepage

    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.

  • Re:hmmm (Score:2, Interesting)

    by Anonymous Coward on Sunday October 18, 2009 @07:40PM (#29788035)

    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 expect gaps in the fossil record. Also most fossils on earth have not been dug up and analyzed by scientists, we only have a small fraction of the record out there and already we can see clear patterns of what is loosely called evolutionary trends.

    Also just because one species "evolves" from another doesn't mean that the so-called "parent" species stops evolving.

    If you really want an example of diverging species look at the Great Dane and Chihuahua or nearly any other domestic species, such as the cow, that has shown great variations between breeds. In the former example mating is nearly impossible. Don't like that? What about Horses/Donkeys? No we don't have records old enough to historically prove it, but the evidence is there.

  • by shovas ( 1605685 ) on Sunday October 18, 2009 @09:07PM (#29788547) Homepage []

    "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 example of evolution, this theme will keep coming up. The information was already there, it just needed to be flipped on or off or the genes reconfigured or recombined.

  • by yndrd1984 ( 730475 ) on Tuesday October 20, 2009 @10:30PM (#29818401)

    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 around - and that adaptation's only effect visible is to prevent it from using a resource. More importantly, any time a new characteristic appears and we don't have a nearly complete understanding of it, it can be described in terms of the loss of information.

    Anyway, you've brought up an important point, and while I do think you're grasping at straws, I can't be sure you're wrong - so I eagerly await the results of the DNA sequencing of these critters so the information theory guys can give us a definitive answer.

All science is either physics or stamp collecting. -- Ernest Rutherford