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.”
And you COMPLETELY MISS my point while making it for me. Evolutionary biologists have already accepted that evolution is a fact and are just looking for pieces that fit into their puzzle and routinely ignore any that do not yet never once do they stop question the basic premise of evolution.
Here, case in point, in the past in order to "convince" (read that "indoctrinate") people as to the validity of the theory of evolution, they used to use a chart of a horse and some smaller horselike creatures that they claimed were ancestors of the horse in some distant epoch. However, when you carefully examine the skeletons you notice that the creatures gained and lost pairs of ribs at random as it "evolved". As more people began to question this, the evolutionists backed off the validity and eventually the chart used to indoctrinate MILLIONS was discredited as innaccurate.
And how many scientist "prove" evolution is to say, well, this extinct critter looks somewhat (or maybe even a lot) like this living critter, so therefore it evolved from this extinct critter.
Yea. Same old, same old. When the old theories start to fall apart, just make up new ones that fit without actually explaining why.
I'm glad you brought that up. I was a programmer in another life and have, in the istant past, written fractal generators and ported a Unix plant fractal generator to Mac. When I heard anti-evolutionists complaining about a lack of 'information' in the genome, computer programs were the first thing that came to mind as an example of code (algorithm) that produces information rather than just reading information.
Rules are tools for understanding. They only exist in the heads of the people that think them. They can be used to describe phenomena but cannot be confused with the phenomena. Rules only model phenomena, it is NOT the other way around.
But I do have faith in truth.<<
FAITH in TRUTH?
Try some real philosophy about knowing!
http://pespmc1.vub.ac.be/EPISTEMI.html
Epistemology, introduction
>>I think you are arguing semantics. If we discover a rule that we observe nature to always follow then isn't it correct to say that nature also follows that rule?<<
NO.
Name a nontrivial rule that nature follows perfectly. I can't think of any. They are all imperfect models. Some are better and more useful. Occam's razor applies here.
E and Pi are tools for understanding.
Universal values. The same values here as on Alpha Centari.<<
How do you KNOW. That is an assertion. Probably correct, but you have not tested it, nor are you able to test your larger imbedded assumption, they are UNIVERSAL values.
IIRC both Pi and E are transcendental numbers. We only have approximations of their values. Very good approximations, but still imperfect approximations. We don't KNOW their values.
http://mathworld.wolfram.com/TranscendentalNumber.html
If you can name that perfect rules "Nature" follows, give me a buzz.
I really would like to know it. But I think you are confused in the arena of Epistemology. How do you know, what you know.
DK
Where did you get the notion that populations don't respond to results? <<
You. Sorry.
Bingo. You are learning. Evolution does not specify a direction or results. That is why probability calculations are irrelevant.<<
How do we evaluate NS? The original article asserts there are 50 species of Stickleback. Can one gene determine a species difference or are they really a set of subspecies perfectly able to reproduce successfully with each other?
Natural Selection has a terrible history of observation. It has squishy definitions to hide its warts.
Hard science biology will have the answers. And evolutionists will have to take their lumps when some of the assumptions based on morphology are kicked aside. Unless, of course, there is corruption in the sciences too.
Nahhh, that would never happen.
LOL
DK
Not from me. Populations change as a result of variation and selection, but variation itself is neither predictable nor guaranteed.
Read it again. Population and probability are intensely related.
But of course when you say that variation is neither predictable nor guaranteed, what is the value of the theory?
Ex Post Facto theory? Theories are about prediction.
You are defending a theory that:
Does not predict outcomes.
Does not guarantee outcomes.
I'm starting to doubt whether your belief qualifies as a theory. I know what it's usefulness is from you conception.
Populations will change, and we cannot know why or how. But it is the result of variation and selection, which we can neither guarantee nor predict.
Doesn't that sound extremely squishy?
DK
"OK, now lets throw in a little natural selection. Every time a correct letter in the correct place is struck, place that letter on a separate piece of paper."
There are two things wrong with this analogy, and I can't believe that Dawkins actually published this (I think this was in the Blind Watchmaker), giving how flawed the analogy is.
This would be a great example of evolution if (1) evolution was directed toward a specific goal, and (2) evolution didn't require the intermediates to be stable. Since both of these are false, the example is meaningless.
A better example is to start with a sentence, and then see how long it takes to morph into a completely different sentence, with all of the intermedia sentences making sense. Of course, this still leaves the problem of the origin of the first sentence, which is still just as problematic and combinatorially improbable as before.
When there were only 3 or 4 specimens in the chain from Hyracotherium to Equus, it seemed obvious to display them as a linear progression. As more and more new fossil species were found, it became obvious that modern Equus is the only surviving twig of a limb that once had many branches and twigs.
That did indeed make people point to some of the earlier charts and say, "We now know it wasn't that simple." It didn't make them point to the chart and say, "We now know horses didn't evolve."
Just correcting your post to be more like the truth. Carry on.
And yet you can find no fossil record of the modern horse.
Relentless and shameless, aren't you? Shall I guess the gimmick is going to be that, if it isn't a modern horse, it's just an extinct thing and "Where are the transitionals?" Whereas, if it IS a modern horse, it's just a modern horse and "Where are the transitionals?"
The profusion of fossils from Hyracotherium to Equus make a nicely fleshed-out tree. This is about the sort of thing we should expect from our models of 1) geology and 2) evolution. Doesn't mean we won't find still more if we keep looking.
The names in the table below are all genera, not species. And yet supposedly we have no fossil record here.
2My Old & New World Equus
\ | /
\ | /
4My Hippidion Equus Stylohipparion
| | Neohipparion Hipparion Cormohipparion
| | Astrohippus | | |
| | Pliohippus ---------------------------
12My Dinohippus Calippus \ | /
| | Pseudhipparion \ | /
| | | |
------------------------------------------- Sinohippus
15My \ | / |
\ | / Megahippus |
17My Merychippus | |
| Anchitherium Hypohippus
| | |
23My Parahippus Anchitherium Archeohippus
| | |
(Kalobatippus?)-----------------------------------------
25My \ | /
\ | /
|
35My |
Miohippus Mesohippus
| |
40My Mesohippus
|
|
|
45My Paleotherium |
| Epihippus
| |
Propalaeotherium | Haplohippus
| | |
50My Pachynolophus | Orohippus
| | |
| | |
------------------------------
\ | /
\ | /
55My Hyracotherium
|
So we have two "sciences" with slightly different information content. Real-World science: the table and link in this post. Loony Science: "And yet you can find no fossil record of the modern horse."
The advantages of each should be obvious. One has more information. The other one is very easy to study.
Some people don't have faith that truth exists. They don't believe there is such a thing as absolute truth. They talk about "my truth" and "your truth".
Name a nontrivial rule that nature follows perfectly. I can't think of any.
What do you mean a non-trivial rule?
The rule for gravitational force I just gave you is followed consistently for special conditions. It doesn't under Einsteinian conditions but that means we haven't found the universal rule yet.
How do you KNOW?
Let me put it to you this way: If you don't believe we know that pi is the same value everywhere then you don't believe you know anything.
We don't KNOW their values.
That's true. But 1)We know there is only one value and 2) We know that it is the same everywhere because the calculation of the values does not depend on any physical constants.
The fact that we don't know the value doesn't say anything about whether there is only one value.
If you can name that perfect rules "Nature" follows, give me a buzz. I really would like to know it.
Yeah. You and a lot of people.
Yes, and there are all kinds of simple formula that create tons of transcendental numbers or "pseudo random" sequences.
I remember a discussion of cosmology years ago and the topic was, "If the universe follows simple rules why is it so complex?" And the typical answer posited random variations in the continuum.
Of course that was before modern computers and the theories of chaos and complexity. Occam's razor says the simplest theory is the correct one. So if the universe can be explained without throwing in "randomness" why do it?
You know what? You've got really, really bad manners. If you want to apologize for that, I will continue the discussion.
Bones generally don't mate.
Don't know?
So I guess nobody can make you see anything?
Can't know?
Things are morphing in stages in the fossil record, the very thing being denied as existing, and your excuse for allowing the denial is that bones are not genes?
So here's the sequence:
Creationist: "There is no fossil record of intermediate forms for horses. There used to be one presented, but science has admitted that that was a fraud."Hello? That there aren't any transitionals is one claim. That fossil bones don't usually contain DNA is another. Bait and switch much? Who do you think you're fooling? Your original claim is false. Got a valid answer?Answer: "There are now more specimens intermediate in form and age between Hyracotherium and Equus than there have ever been. Here's a marvelously detailed tree of horse evolution with all the genera from Point A to Point Z (for zebra?)."
Creationist: "How many of those can mate with a modern horse?"
Anyway, it amuses me to kick again at the new goalpost.
Morphology is not very convincing.
Only if you're fighting Holy-Warrior-style to stay unconvinced and pig-ignorant. Morphological data produce the same phylogenetic trees as molecular biological data to a remarkable degree. How can that happen if morphological data is useless. Molecular biology came along in the last 30 years and validated the tree of life morphology had created over the preceding 200 years. Useless? Is anything sort of whatever you want to be, perchance?
Remember the horse skeleton collection that was used for YEARS to tout evolution in texts, and then was exposed as an evolutionary FRAUD. The curator sorted the skeletons by height.
Actually, I don't know a fraud story involving horse specimens. You'd think I'd have heard of it after six years on these threads. Can you provide a reference to a credible source for this assertion?
But even worse, TALKORIGINS is an evolutionary apologist site.
It is a site which compares creationist claims to the actual scientific literature and thus exposes one creationist falsehood after another. If the claims of the T.O. papers and the actual literature were at variance (say, for instance, claimed transitional fossils were made up or did not have the properties claimed), this would be easy to show. Real scientists would be leading the charge against T.O., not creationists. But in fact what we find is that real, credentialed scientists are the people who write articles FOR T.O.
You would and do dismiss anyone who actually takes the trouble to expose creationist falsehoods ON THE GROUNDS that this person routinely takes the time to read creationist literature and rebut the lies. That is the essence of your charge here. Thus, science must either ignore you, and expose itself to the charge of "ducking the fight" with you, or answer you and be dismissed as "evolutionary-apologist." Catch-22.
No sale. What T.O. has compiled is the real scientific literature on horse evolution. It exists. The guy who says it doesn't exist is the fraud. Your wave-aways are a mix of the irrelevant and implausible.
Morphological species determination is, as I have said before, crap science.
You were wrong before, too, as I demonstrated by the convergence of molecular and morphological data. Guess what, you're still wrong.
NS Evolution is full of squishy definitions, and unsupported assertion about evolutionary "pressures" causing specific changes. NS Evolution does not go after the frauds that have been exposed with vigor.
You're too busy being militantly stupid to know if something is workable or not. The personal fulfilled predictions of Darwin himself include Precambrian life, whale ancestors, human ancestors, the distribution of flightless bird life, and the existence of a particular long-tongued tropical moth. Evolution works. The lying lawyerisms of evolution-deniers attempt to bury knowledge but cannot increase it.
A Question for Creationists: Creationists who wish to deny the evidence of horse evolution should careful consider this: how else can you explain the sequence of horse fossils? Even if creationists insist on ignoring the transitional fossils (many of which have been found), again, how can the unmistakable sequence of these fossils be explained? Did God create Hyracotherium, then kill off Hyracotherium and create some Hyracotherium-Orohippus intermediates, then kill off the intermediates and create Orohippus, then kill off Orohippus and create Epihippus, then allow Epihippus to "microevolve" into Duchesnehippus, then kill off Duchesnehippus and create Mesohippus, then create some Mesohippus-Miohippus intermediates, then create Miohippus, then kill off Mesohippus, etc.....each species coincidentally similar to the species that came just before and came just after?
Creationism utterly fails to explain the sequence of known horse fossils from the last 50 million years. That is, without invoking the "God Created Everything To Look Just Like Evolution Happened" Theory.
I apologize that you do not understand debate, nor reason.
Or for that matter why you know what you do.
Tell me a nontrivial rule that Nature FOLLOWS. At quantuum distances, Einsteinian speeds or Newtonian. We create the models to help us understand nature. It is not the other way around.
All of those models were created to model Nature.
If I were to create a drawing of a model, would you say that the bowl of fruit obeyed my drawing?
DK
I'm sorry if you percieve me as rude. If you have been on these thread very often, I am mild compared to some of the true partisans.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.