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.”
hmm a bit of spew on the end of that which I forgot to remove
Any legible sentence with the same number of letters would have the same probability ... geeze.
My new tagline ... thanks ... that is so funny.
My new tagline ... thanks ... that is so funny.
I believe I answered that assertion by requiring that the a monkey be placed on every square foot of the surface of the Earth. Perhaphs more monkeys ...
If we have one particular phrase in mind then your logic is correct, but if we have thousands of letter combinations that make up the many phrases of Shakespeare works available, the likelihood of any one phrase of the bunch being typed, goes up.
You need to work the numbers ... thousands of phrases possible does not appreciably effect the results. Do the math ... you will see.
Science Daily is a creationist screed?
Do you want to define your self as less than a moron?
I respect boddsmith, for his posts.
But I disagree with his conclusions. Mergers will be a an absolute disgrace for Darwinists.
I know what I need to know, and I thank you for being the opposition. A vigorous discussion led to my discovery of what ToE biologists fear. To cool. It is not creationist, but it is biological.
I'm willing to wait for more, renegade biologists to have fun with real science. You want to pound people heads with the bones of an ass.
Creationist.
DK
This is better explained by speciation than merging. Even if there is some merging Anyway hybridisations are the exception and not the rule as it cannot explain the rise of diversity of life over time. Sure hybridisation can explain new species emerging that lie between two existing species, but it cannot explain the emergance of higher taxon over time. For example merging cannot account for the origin of modern horses given the lack of horse-like species around 60 million years ago for example. Some mechanism other that merging gave rise to horse-like creatures. <<
Horses happen to be one of the few modern examples of cross species breeding. Isn't that an interesting fact?
On your species trees, with mergers, where are the species designations? Crappy logic, crappy definitions.
If your claim is of a rigorous fossil record...that would
be quite frankly, bizarre.
The second assertion, that you have some kind of knowledge at the beginning of life is an argument you would run from. Is a non creationist, I really don't care.
But those trees have a third example you did not pose. Mergers and branches. As I stated before. I don't know the mechanism, for ToE. You assert speciation, and ignore its warts. But you deny hybridization, on convenience.
That is not science.
The article I cited was pretty clear. Hybridization may be a competing mechanism for evolution. It is dismissed without investigation by ToE biologists.
That is a SIN against science. I liked your tree, but as I said, there are both mergers and divergences. It would be a MAJOR scientific embarassment to acknowledge that a those trees, inviolate for decades, to be wrong.
As with any scandal, follow the money (or the prestige)
Evolution is still overall a tree structure, even if there are merges (and they wouldn. <<
With more than three current examples of problems of definition, and an experiment to the contrary,,,
Denial.
Real time, now, replicable, testible, current.
DENIAL.
What has science become.
DK
You are beginning to get it.
Speciation is far more relevant to explain the fossil record than hybridisation. Speciation increases diversity. Hybridisation does not. Hybridisation cannot explain the overall pattern.
Overall the fossil record is a tree with low diversity at its root and higher diversity as time passes. Speciation creates trees. Hybridisation does not (in fact it tends to produce what look like upside down trees - ie a reduction in variety).
And if you think the authors of that news article you posted are claiming that hybridisation would seriously change the evolutionary tree you better read it again.
*it has to be noted that all examples of hybrids today - wolphins, ligers, tigons, mules, etc have never founded stable populations even if these offspring are fertile. They will therefore be unlikely to leave any fossil trace..
I was simply paraphrasing what I read in the article. If I said something that could be construed as a "strawman arguement(sic), weak rhetoric and outright misinformation", please be more specific.
One of the first lessons that I have learned in being an effective listener is to try and repeat back what I heard. Perhaps I misunderstood something in the original post, but I don't believe that I have. I was simply pointing out the far-reaching, weak rhetoric and outright misinformation that is perpetuated by the pro-evolutionists who feel that the promotion of their belief system somehow trumps the necessity of legitimate science.
This topic was posted , thanks PatrickHenry.
How does evolution explain things such as the plethora of vegetation? Trees, flowers, fruits, vegetables, ... Did these also evolve over billions of years after their supposed origin in the primordial ooze?
Survival of the fittest is a reality. Something from nothing??? Yeah, right.
I have - yet another - dumb question:
Aren’t “simple genetic changes” what these Covid “vaccines” result in?
LOL
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