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Evolution happens: Loss of genes produces odd evolutionary change in worms

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Figure 2. External morphological differences between an L2 larva (A) and a dauer larva (B) are shown by scanning electron micrographs of the head.
Dauer vs. normal larva/US NLM, NIH

In “Is Evolution Predictable?” (Science, 17 August 2011), Elizabeth Pennisi tells us that the answer may be yes:

Many biologists have argued that evolution depends on too many chance events to be repeatable. But a new study investigating evolution in three groups of microscopic worms, including the strain that survived the 2003 Columbia space shuttle crash, indicates otherwise. When raised in a lab under crowded conditions, all three underwent the same shift in their development by losing basically the same gene. The work suggests that, to some degree, evolution is predictable.

Okay. Pennisi takes the time to unfold for us the curious life history of the nematode worm, as follows:

A young worm takes one of two life paths: Either it matures in 3 days, reproduces, and dies within 2 weeks, or it goes into a state of suspended animation, remaining what’s called a dauer larva. Dauer larvae don’t eat, and they can survive stressful environmental conditions for months before turning into adults. Typically, too little food, the wrong temperature, or crowded conditions prompt young worms to become dauer larvae.

The worms know whether they should become dauer larvae: They

…. know their numbers are too high because they can sense odor chemicals called pheromones emitted by their peers. When there’s too much pheromone, they choose the dauer route.

But then researchers found that one old lab strain was not following the pattern; it never “dauered.” Under favourable “lab food” conditions, it had lost the genes for that.

So the researchers studied this “evolutionary change” in the strain of worms that flew (and survived) Columbia, and found that the whole strain had lost it.

Other researchers have uncovered instances in fruit flies, cavefish, and stickleback fish wherein evolution has taken the same path more than once. This work is “another excellent example,” says Princeton University evolutionary biologist David Stern. These cases, Bargmann says, are “opening our eyes to a new way of thinking about how evolution happens.”

Yes, evolution happens, but – when detected in nature – it always seems to involve loss of traits. So evolution consists then, of loss of original traits?

7 Replies to “Evolution happens: Loss of genes produces odd evolutionary change in worms

  1. 1
    Mung says:

    Yes, evolution happens, but – when detected in nature – it always seems to involve loss of traits.

    What does that even mean?

    Do young earth creationists even believe that?

  2. 2
    tjguy says:

    Yes, Mung, they do. This is a common argument from young earth creationists. It is VERY rare to find a new gene created by evolution, but changes in an organism that result from a loss of genes are common. ie flightless beetle, blind cave fish, birds that lose the ability to fly, etc. Losing traits is not hard to do. Gaining new traits is almost impossible.
    I think it was Dr. Lee Spetner who wrote the book Not By Chance in which he documented this point very well. He said evolution is like the traveling salesman who loses a few cents on every transaction but hopes to make it up on volume. A great book by the way if you can get your hands on it.
    Dr. Georgia Purdom of Answers in Genesis writes this: I recently read an article in Trends in Genetics (a secular, technical, peer-reviewed scientific journal) entitled, “A golden age for evolutionary genetics? Genomic studies of adaptation in natural populations”. …. At the end of the abstract (a short summary of the article) the authors state, “Nonetheless, most studies of recent evolution involve the loss of traits, and we still understand little of the genetic changes needed in the origin of novel traits.” (Nadeau, Nicole J. and Chris D. Jiggins. 2010. “A golden age for evolutionary genetics? Genomic studies of adaptation in natural populations.” Trends in Genetics 26(11):484-492.)

  3. 3
    Mung says:

    Well, take for example carnivorous plants and animals.

    Did those traits evolve, or were plants and animals pre-built with carnivorous traits?

    And what about all the evolution that has taken place “within kinds” before and especially after the flood?

    All that increase is diversity was brought about by the loss of traits?

    Seems to me an incoherent to hold both that massive and rapid evolution has taken place in the last 6000 years but that it was all due to loss of traits.

    And further, why is that view being put forth on an ID site? News?

  4. 4
    Ilion says:

    Seems to me an incoherent to hold both that massive and rapid evolution has taken place in the last 6000 years but that it was all due to loss of traits.

    Have you thought carefully about that?

    Consider Great Danes and Chihuahuas, Poodles and Dachshunds — is not all this “variation” due to a loss of traits? Hint: yes.

  5. 5
    ScottAndrews says:

    Frontloading seems much more plausible. IMHO the design in nature seems to go beyond just function, exhibiting artistic and entertaining creativity. It’s like painting a house in beautiful colors when plain white inside and out would have done the job just as well. There’s too much to marvel at, learn from, or even laugh at for them to be merely a result of increased or decreased function.

  6. 6
    Dov Henis says:

    Is Evolution Predictable

    Of course it is.
    Nearly. Approximation, proportional to extent of included factors.
    And AFTER comprehending what evolution is…

    A.
    Is Evolution Predictable
    http://news.sciencemag.org/sci.....f4669c78af

    B.
    From DH comment on
    http://www.sciencenews.org/ind.....ine_humans

    Origin And Nature Of Natural Selection

    Life is another mass format, a self-replicating mass format.
    All mass formats are subject to natural selection.
    Natural selection is the delaying conversion of mass to the energy fueling cosmic expansion.
    Cosmic expansion is the reconversion of all the Big Bang singularity mass to energy.

    Natural Selection Updated 2010, Beyond Historical Concepts:

    Natural Selection applies to ALL mass formats. Life, a self-replicating format, is just one of them.
    Natural Selection Defined:

    Natural selection is E (energy) temporarily constrained in an m (mass) format. Period.

    Natural selection is a ubiquitous property of each and every and all cosmic mass, spin array, formats, from the biggest black hole to the smallest physical particle. Mass strives to increase its constrained energy content in attempt to postpone its reconversion to energy and to postpone addition of its constitutional energy to the totality of the cosmic energy that fuels the cosmic expansion going on since Big Bang.

    Dov Henis
    (comments from 22nd century)
    http://universe-life.com/

  7. 7
    Mung says:

    Great Danes have very long legs. Obviously, the trait of short-leggedness has been lost.

    And Dachshunds have very short legs. Obviously the trait of long-leggedness has been lost.

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