Posted on 05/31/2005 12:03:06 PM PDT by PatrickHenry
In a stunning example of evolution at work, scientists have now found that changes in a single gene can produce major changes in the skeletal armor of fish living in the wild.
The surprising results, announced in the March 25, 2005, issue of journal Science, bring new data to long-standing debates about how evolution occurs in natural habitats.
“Our motivation is to try to understand how new animal types evolve in nature,” said molecular geneticist David M. Kingsley, a Howard Hughes Medical Institute investigator at the Stanford University School of Medicine. “People have been interested in whether a few genes are involved, or whether changes in many different genes are required to produce major changes in wild populations.”
The answer, based on new research, is that evolution can occur quickly, with just a few genes changing slightly, allowing newcomers to adapt and populate new and different environments.
In collaboration with zoologist Dolph Schluter, at the University of British Columbia, Vancouver, Canada, and Rick Myers and colleagues at Stanford, Kingsley and graduate student Pamela F. Colosimo focused on a well-studied little fish called the stickleback. The fish — with three bony spines poking up from their backs — live both in the seas and in coastal fresh water habitats all around the northern hemisphere.
Sticklebacks are enormously varied, so much so that in the 19th century naturalists had counted about 50 different species. But since then, biologists have realized most populations are recent descendants of marine sticklebacks. Marine fish colonized new freshwater lakes and streams when the last ice age ended 10,000 to 15,000 years ago. Then they evolved along separate paths, each adapting to the unique environments created by large scale climate change.
“There are really dramatic morphological and physiological adaptations” to the new environments, Kingsley said.
For example, “sticklebacks vary in size and color, reproductive behavior, in skeletal morphology, in jaws and teeth, in the ability to tolerate salt and different temperatures at different latitudes,” he said.
Kingsley, Schluter and their co-workers picked one trait — the fish's armor plating — on which to focus intense research, using the armor as a marker to see how evolution occurred. Sticklebacks that still live in the oceans are virtually covered, from head to tail, with bony plates that offer protection. In contrast, some freshwater sticklebacks have evolved to have almost no body armor.
“It's rather like a military decision, to be either heavily armored and slow, or to be lightly armored and fast,” Kingsley said. “Now, in countless lakes and streams around the world these low-armored types have evolved over and over again. It's one of the oldest and most characteristic differences between stickleback forms. It's a dramatic change: a row of 35 armor plates turning into a small handful of plates - or even no plates at all.”
Using genetic crosses between armored and unarmored fish from wild populations, the research team found that one gene is what makes the difference.
“Now, for the first time, we've been able to identify the actual gene that is controlling this trait,” the armor-plating on the stickleback, Kingsley said
The gene they identified is called Eda, originally named after a human genetic disorder associated with the ectodysplasin pathway, an important part of the embryonic development process. The human disorder, one of the earliest ones studied, is called ectodermal dysplasia.
“It's a famous old syndrome,” Kingsley said. “Charles Darwin talked about it. It's a simple Mendelian trait that controls formation of hair, teeth and sweat glands. Darwin talked about `the toothless men of Sind,' a pedigree (in India) that was striking because many of the men were missing their hair, had very few teeth, and couldn't sweat in hot weather. It's a very unusual constellation of symptoms, and is passed as a unit through families.”
Research had already shown that the Eda gene makes a protein, a signaling molecule called ectodermal dysplasin. This molecule is expressed in ectodermal tissue during development and instructs certain cells to form teeth, hair and sweat glands. It also seems to control the shape of - bones in the forehead and nose.
Now, Kingsley said, “it turns out that armor plate patterns in the fish are controlled by the same gene that creates this clinical disease in humans. And this finding is related to the old argument whether Nature can use the same genes and create other traits in other animals.”
Ordinarily, “you wouldn't look at that gene and say it's an obvious candidate for dramatically changing skeletal structures in wild animals that end up completely viable and healthy,' he said. "Eda gene mutations cause a disease in humans, but not in the fish. So this is the first time mutations have been found in this gene that are not associated with a clinical syndrome. Instead, they cause evolution of a new phenotype in natural populations.”
The research with the wild fish also shows that the same gene is used whenever the low armor trait evolves. “We used sequencing studies to compare the molecular basis of this trait across the northern hemisphere,” said Kingsley. “It doesn't matter where we look, on the Pacific coast, the East coast, in Iceland, everywhere. When these fish evolve this low-armored state they are using the same genetic mechanism. It's happening over and over again. It makes them more fit in all these different locations.”
Because this trait evolves so rapidly after ocean fish colonize new environments, he added, “we wondered whether the genetic variant (the mutant gene) that controls this trait might still exist in the ocean fish. So we collected large numbers of ocean fish with complete armor, and we found a very low level of this genetic variant in the marine population.”
So, he said, “the marine fish actually carry the genes for this alternative state, but at such a low level it is never seen;” all the ocean fish remain well-armored. “But they do have this silent gene that allows this alternative form to emerge if the fish colonize a new freshwater location.”
Also, comparing what happens to the ectodysplasin signaling molecule when its gene is mutated in humans, and in fish, shows a major difference. The human protein suffers "a huge amount of molecular lesions, including deletions, mutations, many types of lesions that would inactivate the protein," Kingsley said.
But in contrast, “in the fish we don't see any mutations that would clearly destroy the protein.” There are some very minor changes in many populations, but these changes do not affect key parts of the molecule. In addition, one population in Japan used the same gene to evolve low armor, but has no changes at all in the protein coding region. Instead, Kingsley said, “the mutations that we have found are, we think, in the (gene's) control regions, which turns the gene on and off on cue.” So it seems that evolution of the fish is based on how the Eda gene is used; how, when and where it is activated during embryonic growth.
Also, to be sure they're working with the correct gene, the research team used genetic engineering techniques to insert the armor-controlling gene into fish “that are normally missing their armor plates. And that puts the plates back on the sides of the fish,” Kingsley said.
“So, this is one of the first cases in vertebrates where it's been possible to track down the genetic mechanism that controls a dramatic change in skeletal pattern, a change that occurs naturally in the wild,” he noted.
“And it turns out that the mechanisms are surprisingly simple. Instead of killing the protein (with mutations), you merely adjust the way it is normally regulated. That allows you to make a major change in a particular body region - and produces a new type of body armor without otherwise harming the fish.”
I don't play either "information" or "math" since neither are my field and I don't think in either language.
However when you say that the information must have been in the bacterial genome, you are playing right at the edge of my field: bio-logic (hyphen intended). Meaning that there are things that are sensible in biological systems that don't make any apparent sense elsewhere.
In this case may I suggest that although the information was
certainly not present in the genome of the bactrium, it was potentially present in the potential of the genome. An awkward phrasing, I know.
DNA is not a fixed structure, it has a very large number of possible configurations, with 4 options for every base pair. Each of those options results in a potential of some kind. Even without the nylon eating information being previously present, the potential for attaining the skill is still there.
I understand what you are saying, maybe I shouldn't either, I think I understand the concepts of "new information" and it makes sense to me, but the intricate details of such a program (my subliminal design language) I may get confused or lost on.
go directly to the source always a better way,
http://www.answersingenesis.org/tj/v17/i3/bacteria.asp
http://www.trueorigin.org/spetner1.asp
this is very long, but scroll down to the more context headings (one specifical refers to "new information") and it includes "math" sorry.
last reply for awhile.
You could read up a bit on the history of science. Darwin called species strong varieties. Biology has never recognized species as a strong barrier to mating. How could it? There are countless examples of fertile hybrids, many known for hundreds of years.
Funny, that was the one I DIDN'T google. But then again...so what.
I think my statement was pretty clear. A hyena may simply be a hyena. As you say...a type unto itself. Maybe it was ALWAYS a hyena or hyena like creature...I think we can only know for certain when a hyena starts evolving into something that is recognizably different from what a hyena currently looks like.
I think you are missing the point here. Evolution asserts that complex things can emerge from following a few rules. To the best of my ability to discern, natural selection and ID differ in the set of rules hypothesized. Evolution asserts that if you start with a self-replicating system that is imperfect, it will evolve in unpredictable ways.
There are lots of speculations on how the first self-replicating system arose, but biology currently has no theory. Science will assume a naturalistic explanation, because that assumption suggests research. Supernatural explanations assert that research is futile.
I'm not the one making assertions. The evolutionary true believers on this forum are the ones making assertions. I am simply saying I don't believe them and I've given the logical reasons why I don't believe them. My personal stance is that I don't know how creation happened or how all these creatures including man, came to be. Maybe it was specific and instantaneous creation by a God, maybe it was gradual evolution, maybe it was evolution through catastrophes, maybe we were seeded by aliens, or maybe there is some other process that we don't know about. Nobody "knows". If there were only one possible theory about how creation came about and all the species came into being, then there would be no cause for argument. But as I have just listed, there are several possible ways this might have happened which is WHY there are arguments about it. Moreover, I don't think there is real proof of any of these things at this point, just assumptions (sometimes sophisticated ones) presumptions, and assertions. I'm willing to let people believe what they want to believe, in lieu of real proof. It may actually be impossible to prove how creation or species came about at all. This is fine with me, but for people who are truly desperate to remove any aspect of religion from our civilization, it is imperative to them to fill the vaccuum of "creationism" (which I don't necessarily buy either, but it's possible to me), with some kind of "scientific" explanation. However that leaves the question that even if everything evolved from a microscopic common ancestor sitting in a pile of primeval goo, how did that little guy come about? People tend to get to lost in the details of DNA and trees and fossil records, etc, and lose track of the basic logic and philosophical arguments involved with this question. It becomes kind of like arguing with people who really believe there are aliens hidden in Area 51 (they have evidence, you know), or that we really didn't go to the moon (they have evidence, you know) or that there was a vast conspiracy to kill JFK and half his relatives and girlfriends (they have evidence, you know). All of these people can go on for hours in very eloquent and sometimes convincing details about their theories - but at some point you have to drill down to the logical and philosphical arguments instead of getting lost in details.
I think the bottom line in this argument is not "what is truth" but the fight between evolutionists and creationists to eliminate or maintain a deity in the equation. As I say, my position is - I DON'T KNOW what the answer is. I have found over time that "I don't know" is the one phrase that almost everyone has a negative reaction too as people crave certainty (THEIR certainty, of course). Maybe this doesn't address your question or issue, but it's my basic position so I wanted to get it out there. To go over the arguments themselves again would simply be endless repetition, so I'm going to refrain from that.
"the one I didn't google..."
Really? Guess what my first hit was on spider agave?
"...so what?..."
You tried to fake it and got caught. That's "so what"
Doesn't do your position much good.
Nice turn of phrase. (Pardon me while I steal that.)
Anyway, yes. "Shucks! Guess I'm a nacheral-borned skeptic." The act is genre fiction. There isn't much of a market for it.
It should be lumped with "I went to public schools and believed all the stuff in biology class. I used to be just what you are. Then I looked into creationism and began to question, if a reptile gave birth to a bird, how that bird ever found another little bird nearby to mate with."
Evolution is learning. The fact that you can learn something in nine days does not suggest the information was already in your head. If you open a combination lock by trial and error, the combination was not in your head before the lock opened. In the case of the nylon eating bacteria, only a digit or two are needed.
But this is how evolution works. A digit at a time.
I didn't "fake" anything. I assumed from the names that they were types of plants. When I googled a couple of them that's what the google search indicated. I didn't go over the site well enough.
But again - so what. Whether they were imaginary plants, or real plants, they were still....plants. It doesn't prove anything one way or another. It was just a childish attempt to "entrap" me rather than debate the issue. I don't engage in childish behavior myself and I like to discourage it.
Mi frase es su frase.
Maybe not. There seems to be a reasonably detailed history there, better than the fossil record of some other groups.
Your ignorance is not proof of anything good. If you don't know what evolution really says or what the evidence for it is, how do you know it's wrong?
Then I looked into creationism and began to question, if a reptile gave birth to a bird, how that bird ever found another little bird nearby to mate with."
Instead of making fun of these people and trying to show how "superior" you are, why don't you answer that question? I've never thought of it myself, but it's not a bad question actually. And answer it in a way that these ingenues or whatever you want to call the people you look down upon, can understand? These people are finding holes in your theory that it is up to YOU and your cohorts to plug up for them. Just deriding people and insulting them is insufficient.
The answer is that if you think that's a problem, you weren't paying any attention in that biology class and your opposition to evolution is based on total abysmal ignorance.
You'll have to go back and re-read my posts. My posts are mainly about lack of proof on the part of evolutionists for their theory. I don't want to keep repeating the same thing over and over. I'm tired of it myself and it just gets to the point of nyah nyah nyah....anyway, my opinion is out there to whatever extent you want to check it out.
That was my point. It was designed by humans, and the evaluation by the human eye to infer intelligent design (without standards) is my point.
>>Evolution asserts that if you start with a self-replicating system that is imperfect, it will evolve in unpredictable ways.<<
But the natural way is to devolve. Aging is a process of devolution, not evolution. Aging is a fairly concrete function of nature for most things living. Humans a just a few other mammals lack the last step in four of generating vitamin C. Only the last step, we have the others. That sounds like devolution, not evolution.
Natural Selection as a pressure to evolve, is not defined. Survival of the fittest does not describe any useful, concrete ideal. Man can run down a horse. How does that have a predictive quality? To be able to analyze that concept you have to "know" what makes something fit by nature.
We don't. We have some guesses. But it is undefined for the most part.
Of course the hard sciences are entering the picture, and squishy definitions and ill defined parameters will be leaving the biological field. Of course everytime I say that, it infuriates the believers of Taxonomy and Morphology.
Natural Selection as the mechanism for evolution will have to firm up a few of those major problems.
It'll be done.
And we will have lots of surprises.
DK
Darby, I actually worked at MIT for about a dozen years and have worked in various other academic and research institutions before and after. The atmosphere and method of "teaching" that you so eloquently describe in this post does indeed prevail in most of these institutions. It is not about "learning" or "proving" or "discovering" or "research" as much as it is about parroting back the establishment's dogma and re-confirming what they already believe. If some one does indeed come up with something truly different or inventive, or that deviates from the mainstream establishment belief, they are indeed treated like heretics and may face consequences for their actions ranging from ridicule and snickering all the way to being nearly forced out of their positions or not getting tenure. I've seen this. In fact, we can ask Larry Summers of Harvard how he now feels about having challenged the orthodoxy of his school about male/female biology, education and choice of careers.
Really? No faking?
I repeat (emphases mine):
you: "the ONE I didn't google..."
me: Guess what my FIRST hit was on spider agave?
you, new version: "....When I googled a COUPLE of them that's what the google search indicated...."
Some alternative explantions are that
1. You confuse yourself easily.
2. You don't pay attention and don't care about accuracy.
3. You deliberately misrepresent
I'm sure there are more.
Most would fit under the category of "childish behavior" you claim not to espouse.
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