Researchers Trace Evolution to Relatively Simple Genetic Changes

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.”

Your first sentence has a problem too, "disprove this theory". True theories can be proved or disproved but "this Theory", evolution, is neither proved or disproved to date. Keep looking for that missing link though, it will keep your hopes up.

Why does the following historical quote come to mind when I read evolution threads on FR:

"The proposition that the sun is the center of the world and does not move from its place is absurd and false philosophically and formally heretical, because it is expressly contrary to the Holy Scripture. The proposition that the earth is not the center of the world and immovable, but that it moves, and also with a diurnal motion, is equally absurd and false philosophically, and theologically considered, at least erroneous in faith."

Can morphology be a definitive assessment for the line between different species?

Not the line between elephant and wheat, but this article claims fifty different species of Sticklebacks.

>>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.<<

Or, in this case, is this difference between "species" more like the difference between red hair and blonde in man? That is one of the real problems facing Evolutionists. Squishy definitions.

The article gives creationists more to crow about. Every time an evolutionist cites a group of species as proof, and it is found later that they are really variants of the same species...well, it should be embarassing.

I like the idea of using "junk DNA" to actually peg speciation, and differences in morphology. I would guess that morphology may have some upsetting times.

DK

The scientific method is quite clear and is the same one that has been used for hundreds of years. A scientific fact is something that is observable, or that can be proven with consistent results by experiement or which has a consistently predictable result.

No a scientific fact is an explaination that has survived rigourous testing to the point that it would be an uncanny coincidence if it weren't true. A scientific fact isn't the same as a mathematical proof. It just requires evidence beyond doubt.

We have fossil data, and we have genetic data, and we have the imagination to generate a hypothesis that man evolved from apelike ancestors. Lets test that hypothesis hard and see if it falls flat. We have enough data that the hypothesis shouldn't stand a chance if it is incorrect.

We observe hominid fossils continue to fit patterns which evolution requires, against the odds. We also observe shared genetic material between modern apes and humans which fits patterns which evolution requires. More importantly we observe shared genetic errors which fit the pattern evolution requires against very high odds.

These are all consistant and repeatable observations. All in all the odds of these observations all fitting the hypothesis are quite low. So low that we can regard the evolution of man from apelike ancestor as a fact.

Now how does evolution of man from apelike ancestor work? That is theoretical, and seperate from the fact that it happened.

We know SCIENTIFICALLY that gravity exists because we are able to experiment upon it consistently and see consistent physical results.

Noone has ever directly observed gravity. We only know it exists from observing its effects.

Equally we also know scientifically that macro-evolution exists because we are able to observe its effects in the fossil record. A higher level of abstraction, but the same underlying process.

But ask yourself do we know how gravity works? No we don't. It is theoretical. We know it exists, but we don't know how it works. The same is true of macro-evolution - we know it exists but not how it works (in fact they are more clueless with how gravity works than they are with how macro-evolution works).

There are NO FACTS behind evolution - only suppositions and assumptions. That's what makes it a THEORY. You folks don't seem to understand what the difference between a scientific fact and a theory is.

So I guess you believe there are no facts behind Quantum Theory, or the Theory of Plate Techtonics, or Atomic Theory huh? Every theory has facts behind it that are trying to be explained.

"Then what does microevolution X 3.5 billion years equal? If it's happening small scale for billions of years, then doesn't that equal large scale over time?"

It's like buying a shoe at the shoestore. If I buy a shoe, when I first get it is fairly stiff and rigid. However, as I walk in my shoe, it will "break in" and become more comfortable. However, the breaking-in process tells me nothing about how my shoe originally got here nor why there are differences between a Reebok and a Nike. It won't get me air pumps in a shoe that doesn't have them, and it won't generate new kinds of material.

Likewise, creationists believe that complex systems do not originate by chance alone. There are small changes, but they are more akin to "breaking in" (whether good or bad changes) than to creating. Now, creationists believe that the "breaking in" process is much more complicated than my description of shoes (which includes modular genomic elements that can rearrange as a result of environment), but ultimately, complex systems are not built from the result of chance and law, but need a designing agent. ID'ers call this the Law of Conservation of Information.

I don't want to continue arguing this issue as it can go on forever and I just don't have the time. However, I will take exception with ONE thing you so flatly state. We don't "KNOW" anything about evolution. It is merely a theory with no facts or proof behind it. I have gone over this over and over again in this thread and I stand behind each and every one of my points. Saying it is so, doesn't make it so. As another poster put it so well a few posts ago, it seems every time an evolutionist comes up with some new "evidence" of evolution is it merely another variation within the same species, i.e., a mutation resulting in lack of armor in a sticklefish. It doesn't matter if a sticklefish mutates with or without armor. It is STILL a sticklefish. It is STILL a fish. It hasn't changed into another species.

I am sick of the arrogance of evolutionists, well demonstrated here repeatedly, and your jesuitical faith in your THEORY. You have no proof of your theory, and you don't even understand the mechanics of it yourself. Unlike gravity you cannot demonstrate its effects. You merely point to similarities between or among creatures in the fossil line and use your "imagination" as an earlier poster put it, to postulate the relationship between different organisms. As I stated before, you cannot conduct (as of this point) an experiment that consistently produces a physical result that demonstrates evolution from one species to another, or from a lower order to a higher. Your experiments, such as they are, seem to be created within the framework of your beliefs and interpreted in a manner consistent with them. You find what you are "looking" for. I would be far more impressed with the results of experiments conducted by someone who had no particular belief in evolution or investment in this theory as that would be a more objective pursuit, with possibly interesting or revolutionary results. At this point, if you were trying to prove the existence of angels, no doubt you could create some "experiments" to prove that as well.

In addition, you have no direct observation of evolution (not variation in a specific species like a flower, but evolution from one type of being to another type)in over 2000 years of recorded history. If gradual evolution were an ongoing process, there would be some species SOMEWHERE that would be evolving into something else and someone would have observed this. There is no record of such an observation (mutated sticklefish don't count, nor indeed do variations in a plant. As a poster said, it's only the difference between blond and redheaded men. Big deal). Therefore evolution does not appear to be part of an ongoing process. Please don't give me the canard about humans not being able to detect evolution within ONE SPECIES. Of course if gradual evolution is true, that would be the case, however, some species somewhere at any given point would be mutating and SOMEONE would have noticed this. Particularly in the past among peoples who observed nature actually far more carefully and from a much closer vantage point than we do. They might not understand the reason but they would have observed the effect.

You do not understand the mechanics of your own theory. All you have is your own belief, and that is insufficient for the rest of us, whether you like it or not. Evolution has large holes and railing against those of us who don't accept your dogmatic utterances is not going to win you any converts.

I don't want to keep posting the same thing over and over - if anyone is interested they can go back and read my earlier comments. I don't have any more time to spend on this today.

Lions and tigers are both FELINES. There is nothing extraordinary about this and it does not prove evolution from lower orders to higher, or from one completely different species to another. I don't think even creationists would argue that mutation does not exist. It is possible that these two animals had an ancestor - who was also a FELINE, and that a mutation occurred, possibly as a result of climate. Who knows. NO ONE DOES.

This is one of the central problems with evolutionists. When you try to demonstrate your theory, you keep doing so with examples that are only variations within a species. Lions and tigers are members of the feline family. Same as little house cats. Big deal.

I am referring to the process by which primeval ooze produced amoebas that somehow became shrimp that somehow became fish, that somehow became frogs, that somehow became reptiles that somehow became mammals, that somehow became primates, that somehow became man.

First of all, you should get your basic facts straight. Evolution does not put shrimp on the human ancestral line

More importantly, though, science does not deal in proof, it deals in evidence.

The molecular phylogeny of living things is strong evidence of common ancestry and of evolution by mutation and natural selection. It allows us to construct evolutionary trees for all of life that agree with the fossil evidence, have the mathematical structure predicted by evolutionary theory, and cannot plausibly be explained by alternative theories.

Obviously I was not being literal in relating shrimp to human beings and I think most people are aware of that. I was referring to the process by which lower orders (according to evolutionists) eventually evolve into higher orders over countless milennia starting with the most primitive organisms of the "primeval ooze" and marching onward through species after species. I could just as easily have inserted the word "blowflies" instead of shrimp and it would have had the same difference.

As for what science deals with - of course until a theory has been PROVEN, whatever evidence exists only supports a THEORY. That theory may be good, bad or indifferent, but it could easily be supplanted by other theories, or changed in radically different ways as PROOF emerges. Evolution is one of the few, if only areas, of science where I read scientists arguing that PROOF is not necessary - only the theory. How bizarre. There are people who claim "evidence" for everything from aliens to palmistry. Is that science too? Well maybe it is - they have "evidence" and they've postulated a theory around it, so I guess it's "science".

Unfortunately this will have to be my last post today on this as I really don't have time (I know, I keep getting seduced into the subject :)

I think what I would find personally helpful and useful in this debate is if evolutionists would start using the phrases "I BELIEVE" or we "BELIEVE" that this is what happens. That would be acceptable to me. What really fries my nose (as Mayor Menino of Boston would say) is statements like "we KNOW" or it's been PROVEN or things of this nature. At this point - we don't KNOW anything. We ASSUME, or we POSTULATE or we BELIEVE. and that's fine as long as we recognize that it is a matter of a theory which is believed and which can change upon the emergence of proof in one direction or another, and that others may have THEORIES that they BELIEVE that may be just as valid - or maybe we're all wrong and something completely different that none of us has currently anticipated is what REALLY happened.

I love it when you scientists turn into 2 year olds talking street jive when you don't have a cogent response. nanny nanny boo boo, you're a doo doo head. I'll tell you the way I told my 2 year olds. Saying it louder don't make it right.

Seriously, I've often tried to think what a secular skeptic of evolution would sound like if I ever encountered one. The best approximation is a guy who used to post on these threads a lot for a few years ending maybe 2 years ago. He posted lots and lots of ID links, mostly from www.ARN.org, and could more or less talk molecular biology issues until he got in with the real MB types. He was semi-literate in science overall. It was all about irreducible complexity and information theory: Behe this and Dembski that. Over time, through, the charade wore thin and some of the Gish-isms started to show through. He was bogus, too, but he had me going for six months or so because he took the time to fake it well. Eventually he announced he was "starting to discover" religious feelings because 1) ID is so convincing and 2) mean old Darwinists are so dogmatic.

I'm now a "secular skeptics of evolution" skeptic. I don't think there is one. You have to ask yourself why a supposed secular skeptic is doing stupendous feats of denial if not from religious horror. It can't be from a complete ignorance of science such as manifested by the typical Young Earth Creationist. He supposedly isn't one of those and doesn't read ICR or AnswersInGenesis to get the only version of science he knows. If he doesn't know any science, he probably realizes it and assumes scientists are doing it at least halfway right--better at any rate then he can do without any preparation.

You basically need some kind of religious horror or other cult attachment. The Raelians would be secular skeptics if they weren't a cult with aliens as God. They reject evolution because the alien civilization that fills the God role in their cult can't do its job if evolution is doing it, same objection as Bible Belt creationism.

Anyway, in your shoes, I'd learn to spell ID. But if you go that way, you'll have to go from total ignorance of everything but everything in science to fascination with biological nanomachines, genetics, biochemistry, and molecular biology in a super hurry. Shall I prepare to be amazed at the transformation?

It was meant as an excercise to the reader ... Just for fun, it is quite easy to prove this is a totally rediculous statement made by an evolutionist with no understanding of mathematics and combinatorics.

For giggles, and in your spare time, assume the following:

1. The monkey only has to produce "To be or not to be, that is the question."
2. Assuming the keys on the typewriter are pressed randomly (dont forget capitals and spacebar depressions), what is the probability of randomly producing the sentence? (104 keys on a keyboard, but to make it fair ... only assume the 26 letters of the alphabet and ignore capitals ... lol)
3. Now assume that every square foot of the Earth has a monkey with a typewriter attempting this.
4. Now assume it takes the money only 1 second to type enough characters to complete the sentence.
5. Now assume the monkeys are at it for 10 billion years.

Is the answer even remotely possible?

Evolutionists assume anything is possible given enough time and time is their excuse when attempting to justify why evolution cannot be observed today.

Fairytale for grownups.

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