Posted on 12/09/2003 7:47:21 AM PST by PatrickHenry
In what has been described as the "perfect experiment," evolutionary biologists at the University of Chicago replaced a single gene in fruit flies and discovered a mechanism by which two different "races" begin to become different species, with one group adapted to life in the tropics and the other suited to cooler climates. The tropical group was more tolerant of starvation but less tolerant of cold. The temperate group was less able to resist starvation but better adapted to cool weather.
The altered gene also changed the flies' pheromones, chemical signals that influence mating behavior. As a result, the researchers show in the Dec. 5 issue of Science, the two groups of flies are not only fit for different environments but may also be on their way to sexual isolation, a crucial divide in the emergence of a new species.
"This study directly connects genetics with evolution," said Chung-I Wu, Ph.D., professor and chairman of ecology and evolution at the University of Chicago and director of the study. For the first time, we were able to demonstrate the vast importance in an evolutionary context of a small genetic change that has already occurred in nature."
"We had the luxury," added co-author Tony Greenberg, Ph.D., a postdoctoral student in Wu's laboratory, "of watching the essential event in Darwinian evolution, the first step in the origin of a new species. We were quite impressed, that this simple alteration played such a dramatic role, both adapting flies to a new environment and changing their sex appeal. Once two groups become sexually isolated, there's no turning back."
The scientists used a new technique to knock out one gene from fruit flies and then replace it with one of two slightly different versions of the same gene.
They focused on a gene called desaturase2 that plays a role in fat metabolism. Flies from Africa and the Caribbean, where there is tremendous competition for food but cold temperatures are not a problem, have one version of ds2. Flies from cooler climates, where there is less competition for food but greater temperature variation, have a smaller, inactive version of ds2.
The same gene plays a role in the production of cuticular hydrocarbons -- waxy, aromatic compounds that coat the abdomen of female flies. A male fly, in a romantic mood, strokes the female's abdomen with his feet, which have sensors that recognize specific hydrocarbons, like a perfume.
In a previous report, Wu's laboratory found most males with the temperate version of the ds2 gene preferred females with the same gene; tropical males preferred tropical females.
"Developing increased cold tolerance was an important step for flies that migrated out of Africa to Europe and Asia," Wu said. The change in pheromones, which altered patterns of sexual attraction, "was a by-product of adaptation to colder weather."
Fruit flies have a migratory history similar to humans. They originated in Africa, spread to Europe and Asia and went on to populate the world. As with humans, there is greater diversity within African flies than between flies from Africa and other continents.
Although fruit flies have been a favorite model for the study of genetics since the early 20th century, recognition of consistent differences between tropical and temperate flies came only in 1995. The discovery, however, "has allowed a lot of analysis of the evolution of adaptive traits," Wu said.
"But this was the first time we have been able to study the process from the very beginning," he added, "to watch the first steps as one species begins to split into two, then seals the bargain by increasing sexual isolation. This is the essence of biodiversity."
Additional authors include Jennifer Moran from the Wu lab and Jerry Coyne of the University of Chicago. The National Institutes of Health and the National Science Foundation funded the study.
For the record I am not a Christian nonetheless a fundy. I do, however, have serious questions about evolutionary theory. Simply put, I am not convinced. I do not discount evolution entirely, but it's far from proven.
That said, I am, without fail, disappointed by every thread ever posted on FR that claims some aspect of evolution has been "proven". I don't think the way to make your case with the undecided like myself is to out and out lie. I can't tell which side utilizes faith over fact more, the evolutionists or the fundamentalists.
Good stuff. Keep 'em coming!
- It's a designed experiment. That proves ID!
- It's a lie!
- It hasn't speciated yet!
- Blasphemy!
- They're interpreting it through their naturalistic materialistic worldview.
- How dare you use the screen name "PatrickHenry"?
- Yeah, but "get your own dirt!"
- This is only micro evolution, not macro evolution
- They said: "... may also be on their way to sexual isolation ..." so it's typical evo weasel wording!
- Playing god is what they are doing.
- The point is this was done MANUALLY, It was NOT observed naturally ...
- ... we as a people aren't all that bright. How much tweaking does it to take to do serious damage.
- A deliberate laboratory forced change does NOT equal natural change.
- Speciation my butt.
I think you're the first one to use "proof" on this thread. Science can never fully prove anything. But experimental evidence comes pretty darn close.
An interesting comment from a poster whose name I can't recall seeing in the evolution threads before. Could you help me out and point to one -- just one will do -- example of a thread which makes the claim of "proof"? To my knowledge, all that these articles do is present evidence in support of the theory, which is all that can ever be done. Oh, if you can also provide me with an example of an "out and out lie" I'd appreciate that too. The examples in your post aren't quite sufficient. The article is anything but a pack of lies.
Oh, thanks for coming through on one of my predicted responses. Yours is #2 on my list.
Y'all noticed this, but you, PH have got their number.
Yes!
I can also predict the ending of Casablanca, having seen it numerous times. Such are my powers of prognostication.
No problem. First, of course, you'll have to make a pact with the devil. The usual terms. We have a few blank contracts lying around somewhere ...
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