New evidence that natural selection is a general driving force behind the origin of species

Vanderbilt University ^ | 23 February 2006 | Staff

[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.]

[muawiyah]

The junk DNA in so terribly many of your genes IS viral DNA.

And, plasmids appear "rod-shaped".

Half a billion years before the "Cambrian Explosion" is probably right. That's why pre-Cambrian multi-cellular fossils have been found.

The sudden appearance of incredible novelty after several billion years of bacterial mats is more than startling.

In fact, it may well be the evidence that the virus is NOT the foundation of all life on Earth as the authors speculated in the piece on mimivirus in February's Discover magazine.

Now, how to test the theory ~ well, we could create a standard, but otherwise "artifical lifeform" (a manmade bacteria) and start plugging in viruses to see what they do. If they create the various enzymes and proteins found in the "higher" lifeforms, that's a start. I suspect some of them, properly arrayed, can be read as instruction books for building devices ~ that would certainly justify the expense creating an artifical lifeform is going to entail.

[darbymcgill]

I think this is it....

[Fester Chugabrew]

I do not place quantum mechanics on the same level of scientific accuracy as biological history concocted from unrecorded, unobserved history. Observed history has always denoted speciation within limits. Quantum mechanics throws into question our very understanding of history.

[Fester Chugabrew]

I do not think electricity is a mental concept, but a driving force. "Natural selection" is hardly a driving force, but an abstract concept that can be applied arbitrarily to any historical event whether it be past, present, or future.

[muawiyah]

"Natural Selection" is the process where by the local "god like process" "Natural" decides which species propers and which species does not.

Sure looks different from Genesis.

[Fester Chugabrew]

Yeah, it looks different. But it's the only truly "scientific" way, you know.

[LiteKeeper]

Creationists have believed in Natural Selection as an explanation for speciation from the beginning.

[muawiyah]

There are, of course, those Creationists who believe the "Age of Prophecy" is closed, as is the "Age of Creation", so God is simply not creating any new species these days.

In the meantime the courts are busy telling us that the "godlike process" Natural Selection is now in charge.

[edsheppa]

The junk DNA in so terribly many of your genes IS viral DNA.

While it is certainly true that some "junk" DNA (about 8% of the 98% of human DNA so considered) is viral DNA, that is not what you said. You said that

your own genes are clustered together the same way as DNA viral genes.

and that is not true.

And, plasmids appear "rod-shaped".

Hmmm, let's take a look:

Nope, not very "rod-shaped" there.

Also, your test has been underway for quite some time now. Viruses routinely infect bacteria. They are called phages. There are even endogenous phages that integrate into the bacterial genome.

[edsheppa]

You're hopeless. I said field, not electricity. Forget it.

[muawiyah]

I'm just quoting from the article several of us are referencing. "Rodlike" is a rather flexibile term.

[Fester Chugabrew]

Hey, this article calls "natural selection" a "driving force." I maintain it is nothing of the kind. Energy is a driving force. The word "natural" is hardly scientific in its own right. It is philosophical. The word "selection" is abstract. It may or may not have a basis in reality depending on how it is applied, and as such it has little place where more exact science is concerned.

[Fester Chugabrew]

Natural selection, when offered up as a "driving force," pretends to "answer every question" when it comes to the origin of species. In fact, it is only one of many possible explanations.

[Fester Chugabrew]

Origin of species? As in, "the very cause of the first possibility of distinguishing one species from another"? Science is still undecided as to what constitutes one species from another. Or is it solely the incapacity to reproduce? There are humans who cannot reproduce with other humans. Does that make them a different species?

If you want to talk about hopeless, then talk about those who think matter can organize itself apart from intelligence, design, or some combination of the two.

[Alamo-Girl]

Thanks for the ping!

[Thatcherite]

What's your concept of Zenos Paradox, muawiyah?

I noticed that piece of nonsense too. (which seemed to cause unseemly hilarity on the OP's part, which was odd, because I didn't say anything funny, and my post in no way resembled Zeno's paradox.)

[Thatcherite]

Look, if they don't taste the same a million years from now, you get back to me ya' hear!

So your claim wasn't based on any actual knowledge or information. Just a bald assertion that you cannot back up. OK.

[Thatcherite]

Creationists have believed in Natural Selection as an explanation for speciation from the beginning.

Except of course for those creationists who don't. (numerous on these threads deny that speciation *ever* occurs, perhaps a majority).

[dread78645]

... it refers to "isolated breeding groups" as constituting a "species".

By that definition, I have an aquarium of 'Endangered Species'.
Not to mention just about anybody who keeps cats, dogs, hamsters ...

[PatrickHenry]

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