Changing One Gene Launches New Fly Species

Science Daily ^ | 08 December 2003 | Staff

[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.

[wideminded]

Experiments in which two different lines of fruit flies adapted to different environments are developed have been done before. This experiment changed the pheromones of the fruit flies, but I believe that in order to be classified as separate species the two lines must be incapable of mating and producing offspring. The article only states that they "may be on their way to sexual isolation."

[Michael_Michaelangelo]

I was thinking the same thing! It's pretty much been obvious that there has been NO speciation observed, as the evo's fearless leader so valiently claims at post #1. But that isn't going to stop their party. The show must go on!

Time to employ the meter!

[laotzu]

"Take away their Faith and their world collapses upon them."

Assuming this to be true; what kind of person would delight in taking away their 'Faith', and collapsing their world?

What, do you think, would motivate such cruelty?

[DennisR]

But a 30% reproductive rate is still a recipe for extinction. It would take only a few generations for the new species to become essentially unreproducible as the probability of finding a match converges to 0.0, at which time there would be probabalistically no chance for the species to procreate. The only way a species can continue indefinitely is if there is 100% compatibility.

[DennisR]

I am a creationist and an IDer and I do believe in genes. So what you have stated is a falsehood.

[laotzu]

Have I said something wrong?

[Elsie]

I got some that live along streams in the American Southwest that are very nearly what you seek. These little demons fly Fast, and straight at you; take a chomp and keep on going. I swear that each bite feels like a B-B has hit my skin!

I've escaped their wrath only by RUNNING away from their territory!

[Elsie]

If evolution is based on chance mutation, the odds of several fruit flys altering in the same way, that one gene, are slim.

HEY!!!

---

You are NOT supposed to point this out!!!

[Elsie]

I'm not aware of any scientific theory that postulates lizards changing into rabbits.

By THIS statement, you show yourself to be a "C" person.

[Merdoug]

First you insult me, then you expect an answer. Okay. I'll give you one. I believe in Truth. No matter how unpleasent. I can't believe in a fairy-tale. Take away the pomp and ceremony and the World's religions are nothing more than Santa Claus: it's belief in something that does not exist. It's fantasy-world. When someone builds their foundation of Life on something not real, they will never let anyone break their belief, or else they have no reason to live. I will never change your mind that there is no God, so don't bring on the sob story that I am going to hurt your faith. I have no desire to change your mind, but I get so frustrated by people sometimes, who are happier than me; who don't think the way I do; that don't see the cold, nothingness that waits for us after life. I cherish life and yet I see a world that I consider so unfair and evil that I cannot change. I get depressed. I lash out at people like you who have the comfort of religion. I can't do that. I am what I am. Today, I was in a resturant and was ordering to-go. I know that the pretty girl who took my order will never be interested in me: she probably has some hunky guy that she dates. I am so much better; I could give so much more to her, but THAT IS LIFE. IT IS UNFAIR. It is not cookie-cutter wonderland, where good people win and bad people are punished, and there is no heaven and hell at the end to meet out justice. It just depresses me sometimes. Sorry if I hurt your feelings.

[laotzu]

"First you insult me...sob story that I am going to hurt your faith...."

I never insulted you. I never mentioned my faith, or even that I had one. Never. You have invented attributes, of mine, with which to be angry.

"....but I get so frustrated by people sometimes, who are happier than me; who don't think the way I do..."

Here is the truth that allows happiness: After for food, shelter, and clothing; happiness is nothing more than a decision you make. Just a decision.

[Michael_Michaelangelo]

Speaking of ID and genes, here's a nice article profiling work that is being done to understand the proofreading ability of RNAP, an enzyme that copies genes from DNA onto RNA.

ScienceDaily

From the article: "Using the optical clamp, researchers found that RNAP does not move at a steady pace along the DNA double helix but rather undergoes a fitful series of unexplained starts and stops."

[ColdSteelTalon]

evolutionary biologists at the University of Chicago replaced a single gene in fruit flies and discovered .

Sounds like a creator is being involved with the emergence of the new specials.

[Last Visible Dog]

I believe in Truth. No matter how unpleasent. I can't believe in a fairy-tale. Take away the pomp and ceremony and the World's religions are nothing more than Santa Claus: it's belief in something that does not exist. It's fantasy-world.

Your statement contradicts itself. First you say you "believe" in truth and then you go on to present your opinion as if it were "truth" or "fact". Claiming the world's religions are nothing more than Santa Claus is NOT the truth nor is it fact - it is your personal opinion and claiming it is the "truth" makes it YOUR personal fairytale - YOUR fantasy-world.

[Merdoug]

My bad. I should have written "in my opinion". Good enough for you? :)

[Skywalk]

Actually, by definition, almost all faiths must be false in some way.

Thus the only fantasy world is that constructed by the members of those false faiths.

[Skywalk]

You know what is funny about you?

I remember a thread where you disingenuously tried to position yourself as some sort of neutralist on this issue. Do you recall that? You were lying then, but at least in your attacks you are being more true to yourself.


Creationist.

[Last Visible Dog]

My bad. I should have written "in my opinion". Good enough for you? :)

My point is nobody knows the complete reality of the religious experience. Is God real? Is one religion THE religion? Are all religions fantasy? We just don't know. Claiming "the world's religions are nothing more than Santa Claus" is not the "truth" and believing this does not mean you believe the truth.

Believers and non-believers stand on the same ground and neither is "firmer" – neither side can prove their position.

Passing judgment on believers is not based in “truth” – it is merely passing judgment on people based on your personal biases and opinions.

[Merdoug]

I'm sorry. I mistook you for another person who wrote a reply to me. As for making a decision, I don't think like that. I choose what I believe to be right until I learn evidence to the contrary. I do not make a "decision" and then close my eyes and ignore the rest of the world or progressing knowledge. I see no reason to believe in a book written thousands of years ago by MEN. It is no different than any other myths of Gods. History has shown that parts of it are contradictory, parts have changed, parts don't match with known history, and parts have been weeded-out to make the present book. Believe in it if you want; you will be happier that way. I just can't believe in something that I cannot SEE and fell to be true. IF there IS a God, I have no wish to meet him. All that I see in this world is cruelty and misery. The Bible's whole concept of sin is ridiculous. I will not blame myself for the feelings that I was born with. Original sin is just more gobble-de-gook that comes from ancient people who tried to explain a world that they could not comprehend. People fear death and they want to know there is something after. People see injustice and they want to believe justice will be given. Why do you think religion is so strong with the poor? It's because THEY are the ones suffering the most and it is to they that Christianity promises the most. It's an incideous belief, but I guess it does give comfort to those without hope. I'll quit here before I bore you too much. I'm different than you: you appear to have found your answers; I'm still looking. I want to believe that there is some "good" end in Life and why things happen the way they do.

[Last Visible Dog]

You know what is funny about you?

Hopefully a lot – I consider myself a fun person.

I remember a thread where you disingenuously tried to position yourself as some sort of neutralist on this issue. Do you recall that? You were lying then, but at least in your attacks you are being more true to yourself.

I am neutralist. I was not lying. What attacks? What the HELL are you talking about?

I once typed in a description of myself that I “love God” when I meant to type “want to love God”. You see, from a sentiment perspective I want to have the complete experience of loving God and actually believing it but currently I don’t have that conviction. I have an open mind which is the essence of being a “neutralist” – I can see both sides unlike many evolutionists or many devout believers.

Creationist.

Yes and No (simultaneously). I believe it is possible the universe was created and I believe it is possible the universe evolved into existence. There seems to be more evidence for creation when it come to the creation of the universe (big bang) and the creation of life but there seems to be more evidence for evolution related to the creation of man.

Open-mindedness really freaks some people out – is that your problem?