Posted on 02/24/2006 4:12:32 AM PST by PatrickHenry
Charles Darwin would undoubtedly be both pleased and chagrined.
The famous scientist would be pleased because a study published online this week provides the first clear evidence that natural selection, his favored mechanism of evolution, drives the process of species formation in a wide variety of plants and animals. But he would be chagrined because it has taken nearly 150 years to do so.
What Darwin did in his revolutionary treatise, “On the Origin of Species,” was to explain how much of the extraordinary variety of biological traits possessed by plants and animals arises from a single process, natural selection. Since then a large number of studies and observations have supported and extended his original work. However, linking natural selection to the origin of the 30 to 100 million different species estimated to inhabit the earth, has proven considerably more elusive.
In the last 20 years, studies of a number of specific species have demonstrated that natural selection can cause sub-populations to adapt to new environments in ways that reduce their ability to interbreed, an essential first step in the formation of a new species. However, biologists have not known whether these cases represent special exceptions or illustrate a general rule.
The new study – published online in the Proceedings of the National Academy of Sciences – provides empirical support for the proposition that natural selection is a general force behind the formation of new species by analyzing the relationship between natural selection and the ability to interbreed in hundreds of different organisms – ranging from plants through insects, fish, frogs and birds – and finding that the overall link between them is positive.
“This helps fill a big gap that has existed in evolutionary studies,” says Daniel Funk, assistant professor of biological sciences at Vanderbilt University. He authored the study with Patrik Nosil from Simon Fraser University in British Columbia and William J. Etges from the University of Arkansas. “We have known for some time that when species invade a new environment or ecological niche, a common result is the formation of a great diversity of new species. However, we haven’t really understood how or whether the process of adaptation generally drives this pattern of species diversification.”
The specific question that Funk and his colleagues set out to answer is whether there is a positive link between the degree of adaptation to different environments by closely related groups and the extent to which they can interbreed, what biologists call reproductive isolation.
Funk and his colleagues saw a way to address this question by extending a method pioneered by two scientists in a now classic study of species formation in fruit flies published in 1989. The original method measured the way in which reproductive isolation varies with time. It proved to be very powerful and a number of other researchers applied it to additional species. Funk and his colleagues realized that if they used the results of these studies and added an ecological dimension then they would have an approach capable of measuring the link between natural selection and reproductive isolation.
“We thought that the idea itself was important, that this is a really powerful approach to a very major question,” says Funk, “but we thought that there was no way in the world that we were actually going to get statistically significant results.”
The reason for his doubt was the incompleteness and lack of uniformity of ecological data. “There are all these species out there and so few of them are known in intimate detail, so any kind of ecological characterization, through no fault of ecologists, will be limited in accuracy and precision,” Funk says.
Nevertheless, the researchers decided to do the best they could with the information available. So they collected information from the published literature on three basic ecological variables: habitat, diet and size. Then they used this information to calculate the differences in ecological adaptation between the hundreds of pairs of related species in the original studies.
When they compared these differences in adaptation with the degree of reproductive isolation for each pair and then added them up, the researchers found that the overall association was positive with a surprisingly high level of confidence: The odds that the association is simply due to chance are only one in 250, substantially higher than the standard confidence level of one chance in 20 that scientists demand.
“The fact that the association is statistically significant despite the crudeness of our estimates suggests that the true biological association is very strong,” Funk says. “Darwin’s famous book was called ‘On the Origin of Species,’ but it was really about natural selection on traits rather than species formation. Since our study suggests that natural selection is a general cause of species formation, it seems that Darwin chose an appropriate title after all.”
[Omitted contact info which is at the end of the article.]
Name one breed and site evidence.
1) That's artificial selection
So is the fruit fly experiment in the article and I believe the proof of most theory is done artificially in the laboratory.
3) This artificial selection is a great support for natural selection
I have a hard time seeing it that way. All of the evidence seems to point the other way.
1) Natural selection isn't defined by speciation. It's defined by adaptation to the environment. There is nothing about the fact that people can interbreed that goes against this. 2) A few thousand years is a very short time for speciation to happen. Isolation is not a guarantee that speciation will happen.
From the article.
In the last 20 years, studies of a number of specific species have demonstrated that natural selection can cause sub-populations to adapt to new environments in ways that reduce their ability to interbreed, an essential first step in the formation of a new species. However, biologists have not known whether these cases represent special exceptions or illustrate a general rule.
The article seem to suggest that the definitive proof of evolution would be the “sub-populations to adapt to new environments in ways that reduce their ability to interbreed” and that has always been my understanding of Darwin’s theory (remember his finches).
Darwin was well aware of selective breeding, far more than you. People have not been trying to make new species. And we have been at it for only a very short time even if we were. That being said, scientists have witnessed speciation.
Estimates I have read is that dogs have been domesticated for between 50 and 100,000 years that’s between 25 and 50 thousand generations. Specialized breeding would have started about 5 to 8 thousand years ago or 2.5 to 4 thousand generations ago with no change in the ability to breed with the root population.
Intension has nothing to do with it; according to Darwin’s theory dogs should be a new species and should not be able to breed with wolves.
It was just "rhetorical" support. Sometimes things are just "koinkydinks" and not part of a chain of causality.
NO they are not
Zebras are more closely related to the Ass and can not successfully mate with the horse.
I think the virus theory may have merit.
Interesting. If you knew anything about hypothesis testing, design of experiments, or statistical analysis, I don't think you would make a comment like that about this study.
I thought it was quite interesting the way the "wild dogs" and "Indian dogs" in the Americas could be shuffled in and among an existing Eur-Asian group even though these animals "bark" much more like their African cousins.
The supposition is that originally dogs didn't bark much, if at all, and that may well have been the primary reason humans "selected" any particular wolfcub for domestication.
I wish they'd kept on that track ~ dogs down the street bark all the time.
Let me assure you I've seen charleton's and true believers misuse statistics before, and this article falls in that category.
If you can hold'em still, a chihuahua and bullmastif can breed quite successfully. Remember, with dogs it's just a matter of cycles and chemistry ~ they really aren't terribly selective, eh?!
The first is dogs.
I'd pay to see you try to cause a successful union between a Great Dane and a teacup poodle.
The second is Man.
Man is amongst the slowest breeders in the world, and there has been no significant biological isolation of note for humans on this planet, by comparison to our leasurely breeding speed.
the third is horses.
Do you know what jennies and mules are? I suggest you look it up if you don't.
Creationoids don't have any understanding of probability or how to apply it, but think they do because the answers they make up support their religion.
Of course the author might actually have that crystal ball showing him that this leaf beatle actually does evolve into a new species. In that case his claim that it was "in the process of transforming into a new species" could still be in concert with your statement that "Speciation is ONE end product of natural selection. It is not the only one."
If this crystal ball doesn't exist then he is making the typical macro-evo leap-of-faith and stating something he thinks/hopes/prays will happen.
Unlike you of course because you stated that speciation isn't the only result of natural selection. Bravo.
But, when it comes to dogs, it's not all "natural".
Buddy of mine is a cat breeder. It's worse!
What is your basis for this statement? Where is the methodology in this study flawed? Argument for argument's sake is a waste of time, dear muawiyah.
???
What the article is saying is that if half of the other possible universes could still have lead to some form of life, even though formed with different properties than our own, then the odds are not 1 in one part in 1010123 (or whatever the number was supposed to be), but 1 in 2.
In other words, the Penrose calculation was about the particular set of physical properties of our universe, and not the chances of the existence of a universe with a set of properties which could still sustain life, even if those properties differed from our own. However, it is this later claim about life that some ID creationists are using Penrose to support.
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