Posted on 10/07/2006 9:08:18 AM PDT by PatrickHenry
Evidence for punctuated equilibrium lies in the genetic sequences of many organisms, according to a study in this week's Science. Researchers report that about a third of reconstructed phylogenetic trees of animals, plants, and fungi reveal periods of rapid molecular evolution.
"We've never really known to what extent punctuated equilibrium is a general phenomenon in speciation," said Douglas Erwin of the National Museum of Natural History in Washington, D.C., who was not involved in the study. Since its introduction by Stephen Jay Gould and Niles Eldredge in the 1970s, the theory of punctuated equilibrium -- that evolution usually proceeds slowly but is punctuated by short bursts of rapid evolution associated with speciation -- has been extremely contentious among paleontologists and evolutionary biologists.
While most studies of punctuated equilibrium have come from analyses of the fossil record, Mark Pagel and his colleagues at the University of Reading, UK, instead examined phylogenetic trees generated from genetic sequences of closely related organisms.
Based on the number of speciation events and the nucleotide differences between species in each tree, the researchers used a statistical test to measure the amount of nucleotide divergence likely due to gradual evolution and the amount likely due to rapid changes around the time of speciation.
They found statistically significant evidence of punctuated evolution in 30% to 35% of the phylogenetic trees they examined. The remaining trees showed only evidence of gradual evolution.
Among the trees showing some evidence of punctuated equilibrium, the authors performed further tests to determine the size of the effect. They found that punctuated evolution could account for about 22% of nucleotide changes in the trees, leaving gradual evolution responsible for the other 78% of divergence between species.
Pagel and his colleagues were surprised that rapid evolution appears to contribute so much in some lineages, he said. "I would have maybe expected it to be half that much," he told The Scientist.
The researchers also found that rapid bursts of evolution appear to have occurred in many more plants and fungi than animals. Genetic alterations such as hybridization or changes in ploidy could allow rapid speciation, Pagel said, and these mechanisms are much more common in plants and fungi than in animals.
"Their result is pretty interesting, particularly the fact that they got so much more from plants and fungi than they did from animals, which I don't think most people would expect," Erwin told The Scientist.
However, it's possible that the analysis could be flawed, because the authors didn't take into account extinction rates in different phylogenetic trees when they determined the total number of speciation events, according to Douglas Futuyma of the State University of New York at Stony Brook, who was not involved in the study. But "they've got a very interesting case," he added. "I certainly think that this warrants more attention."
According to Pagel, the results suggest that other studies may have misdated some evolutionary events. Dates derived from molecular clocks assumed to have a slow, even tempo will place species divergences too far in the past, he said, since genetic change assumed to take place gradually may have happened very quickly.
"These kinds of events could really undo any notion of a molecular clock -- or at least one would have to be very careful about it," Futuyma told The Scientist.
Well known evolutionary mechanisms could account for rapid genetic change at speciation, Pagel said. Speciation often takes place when a population of organisms is isolated, which means that genetic drift in a small population or fast adaptation to a new niche could induce rapid evolutionary change.
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[Lots of links are in the original article, but not reproduced above.]
No. I believe it starkly outlines the fact that this sort of popularized psuedo-Science is nothing but easily debunked propaganda for those whose raison d'etre is to try and find a way to remove the Creator from the equation.
You can win with some people. If you state facts in a forthright manner, and express confidence in your conclusions, the creationists complain that you're being dogmatic. But if you state facts in the traditional manner, as being tentative and subject to further verification, with conclusions expressed in the subjunctive mode, the creationists complain that we're just putting out a bunch of "maybes." So I guess they're going to complain in any event. Might as well ignore them.
Do you believe in "punctuated equilibrium"?
Do you see any proofs for "punctuated equilibrium" in the article you posted?
*ahem* There isn't a fact to be found in this piece.
In the history of the world, only a tiny fraction of all the people who ever lived have had the opportunity to ask highly qualified scientists direct questions, and learn from their wisdom. Happily, because of the internet and places like FR, it is now possible for people from all walks of life to converse directly with all sorts of scientific experts; we have physicists, microbiologists, mathematicians, astronomers, and chemists, to specify but a few, roaming these threads, and eager to explain what they know and how they know it to virtually anyone willing to ask an intelligent question.But there is another segment of people on these threads who, instead of asking these learned folks intelligent questions and thus expanding their knowledge and understanding, insist instead upon bludgeoning them with their ignorance, and questioning the patriotism, honesty, and intellect of people who have dedicated their lives to the pursuit of scientific knowledge.
I submit that such people are not here to learn anything, but are in fact interested in quite the opposite. I submit they are here to interfere with the dissemination of scientific knowledge that they find offensive. They don't want other people to ask the experts questions and learn from them; no, they are here to attack the experts and cast doubt upon their wisdom, in the desperate hope that others will turn away and not listen to them.
IMHO that is why the same people show up over and over again parroting the same refuted diatribes and misinformation, and spewing the same bogus out-of-context quotes designed specifically to disrupt the dissemination of scientific knowledge. That's why the same people show up over and over again misrepresenting what scientific theories and laws are, despite having had it explained to them 1720th time; they are here to instill confusion and spread their ignorance, not to disseminate knowledge.
The experts here on these threads ought to be revered and thanked for sharing with us their insights and explanations of the natural world around us; instead scorn is heaped upon them and their knowledge by the belligerently ignorant. I submit that these purveyors of unknowledge should be treated for the intellectual disruptors that they are. They stare the best opportunity any of us will ever have to gain more insight and understanding in the eye, and spit in the faces of those who offer and have the knowledge to help make that a reality.
Behold, I give you the belligerently ignorant, the intellectual Luddites of our time. Know them for the anti-knowledge disruptors they are.
Do you believe in "punctuated equilibrium," or see any evidence in this piece of writing that we are discussing for such?
On that we are agreed, then.
I already did. The substance of this article, if it was placed on a scale, would be outweighed by a feather.
Also, how have you discerned motives regarding a Creator?
A simple personal observation about most purveyors of evolutionary dogma. Not all, but most.
It really isn't nice for you to put words in my mouth. Obviously, that isn't what I said. Is that sort of inaccurate portrayal of easily determined fact an example of your honesty in handling facts that aren't so easy to discern?
Funny, but someone on one of these threads once told me that most animals and plants never become fossils. If that is so, how is there an "extensive fossil record"?
If I cared to do so, it would certainly be easier than proving the existence in reality of any example of "punctuated equilibrium."
I guess you failed to read my opening comment:
Pure propaganda. The usual mix of unsubstantiated opening statements of certitude, mixed with the usual slide into the vaguest of "maybes".
Can you see how some folks might consider "punctuated equilibrium" to be little more than a weak attempt by evolutionists to create an unverifiable mode of dispensing with some of the many problems that exist with their existing timelines?
And which is it that is the only theory being taught in public schools today?
The weight of proof falls on the proponents of this wild theory. To date, they have provided none. This article presented none. Just speculation and opinion.
Scientific statements are always tentative; pointing this out does not falsify any scientific claim.
Articles in "Science" don't prove any "scientific" claim.
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