Wednesday, September 17, 2008

Ever think of a fruit fly hanging out at the bar trying to “pick up” another fly?

Sure some people change their behaviors around certain people, but surely that only occurs in humans. Think again. According to neurogeneticist Joel Levine, of the University of Toronto, “insects alter their behavior depending on who they hang out with, even mating more frequently in the company of strangers.” This new research is providing more clues on the evolution of social behavior.

Fruit flies obviously do not talk, but they emit 23 identified varieties of pheromones, which the flies can blend into various combinations to “say” or mean something different. They also change their behavior patterns and sleep patterns depending on the “number and relatedness of the other flies they are with,” leading Levine to experiment with these insects to further understand what is influencing this reaction. In their first experiment they divided the flies into vials of forty males, with some vials containing nearly genetically identical flies, and others containing a mixture of genetically identical flies and non-genetically identical flies. The outcome of this experiment led them to believe that the “pheromones important for courtship and mating were affected most by the social context…how a fly reacts [pheromone-wise] to another fly depends on who he has been hanging out with.” Sounds like a very familiar situation that occurs almost regularly in the human population. Others’ behaviors effect how one reacts.

In his other experiment, he tested whether males in mixed groups would behave different in the presence of females. In some vials he had six genetically identical males with six virgin females, while the other vials had four genetically identical males, two different males and six females. What Levine found was that the flies that were in with males unlike themselves sent them into “sex overdrive: they mated 33% more often” than the other set of flies. This is showing that fruit flies are sensitive to their environment, and that mating behavior may not be as hard-wired as once thought; indicating the discovery of plasticity in this behavior. So after all maybe we are just like fruit flies in the aspect of social behavior.

Posted by: Katie Cole (1)


At 5:21 PM, Blogger PWH said...

During the second experiment there were two vials testing how males reacted with other males when in the presence of females. The vial with genetically different males had greater sexual activity. This greater activity could be attributed to the flies wanting to pass on there genes more when other males with a different set of genes are in the same vial. Do you think this could have something to do with competition to pass on ones genes?

Rob Lubenow

At 6:03 PM, Blogger PWH said...

I found this article very interesting because I often wonder about animals social behavior and how it can relate to humans. For example, I have two dogs and one is younger than the other so the older one was extremely jealous when we got the younger one and he always tried to draw attention toward himself. This kind of reminds me of humans and sibling rivalry. Did you come across any other animals that have similar social behaviors to humans?
Chantal Gomes

At 4:34 PM, Anonymous Anonymous said...

I found this to be an interesting very interesting social behavior. I would have never thought that flies exhibit such an behavior. The vial with the flies of all the same genes, did they compete against each other for mates?

Duy Nguyen

At 11:40 PM, Anonymous Anonymous said...

In the first experiment, they divided the flies into vials of genetically identical and mixed genetics. What actually happened in the experiment? What were the methods that they used? You just wrote about what they concluded from the outcome. I just assumed that they observed what the flies were doing for both the experiments.

You included the fact about the pheromones, and I was wondering did they identity which particular pheromone was used by the flies during the experiments.

The behavior of a fly also depends on the number of flies it is with. It seems that their experiments though didn't concentrate on that factor.


At 9:10 AM, Blogger PWH said...

Interesting article. It's always amazing to see even the most basic insects can have social behaviors so like that of humans.Do you think that the flies in the vials with the flies that were genetically similar mated less because they would basically be passing on very similar genes and did not find it necessary to mate more? Do you know what the female flies role in all of this is? In other words does it mention if she chooses any one genetic type over the other based on just the fact that there were more or less of that gene type available?

Lindsay Goodyear

At 1:22 PM, Anonymous Anonymous said...

I found it very interesting that flies and humans sometimes behave in the same way. The first experiment was a little unclear about the outcome; how did the pheromones affect the behaviors? In the second experiment, the genetically similar flies were less eager to compete. Could this be some form of altruism which the flies know to sacrifice a little since the same genes will be passed on no matter what?

Hanbing Guo

At 6:26 PM, Anonymous Anonymous said...

Interesting article and an interesting experiment. It isn't surprising however that likes do alter their behavior to their social environment because many different animals and insects do, but it is interesting in the way they do it with the different pheromones.

Alex Pavidapha

At 8:42 PM, Anonymous Anonymous said...

It is very interesting that a fruit fly's environment has an impact on its behavior. I wonder why males mated more frequently when in the presence of flies unlike themselves. Is it an increased desire to pass on their own genes? I like that your post relates human behavior to fruit flies.

Amy Kawazoe

At 8:47 PM, Anonymous Anonymous said...

I would never have thought to test this out with flies, so this article is pretty cool. I was wondering if the second vial also had virgin female flies, or if that was implied? Also do you know how flies mate or if a female can have more than one batch of eggs because if they can that may have contributed to why the genetically different batch got more action.

Ada Marie Flores

At 9:57 PM, Anonymous Anonymous said...

This article really makes you think about how similar different species really are. To think flies act differently based on who they are around is very interesting. The range of pheromones is impressive, especially that they use different combinations to "say" things to each other. It makes you realize how important communication is even in insects. I would be curious to know what drove the flies who were mixed with genetically different flies to have such high sex drives.

posted by Julie Riley

At 10:07 PM, Anonymous Anonymous said...

I don't know if the article you read covered this, but is there any change of behavior in females depending on the number of flies or genotypes surrounding them? Were there any hypotheses drawn that that vials of mixed males could be the result of greater sexual competition?

Stephen Lee

At 11:15 PM, Anonymous Anonymous said...

It's interesting how the genetically identical flies seemed to be threatened by the presents of the non-genetically identical flies. It's like they thought because the were genetically different from them there wasn't a level playing field. They had up increase their game to increase their chances of mating with one of the females. After reading your entry and the article, I was wondering did the behavior of the females differ in each vial? If there were differences could that have factored in why the genetically identical flies reacted in the way they did?

Posted by: Debbie Theodat


At 11:48 PM, Anonymous Anonymous said...

First of all i love your title. On the second experiment you said "In some vials he had six genetically identical males with six virgin females. while the other vials had four genetically identical males, two different males and six females." So the females in the second vials not virgins, and is there a reason for the females being virgins in the first vial? I mean do the male flies respond better, or do they even realize that the females are virgin? Sorry i ranted on, i really thought that your blog was interesting and well written.

Tenzing Y.Dundutsang

At 10:11 AM, Anonymous Anonymous said...

In the first experiment the researchers “hourly extracted and analyzed the pheromone blends from individual flies from each vial.” The males with nearly the same genetic makeup produced one blend of pheromones, while the mixed group of flies produced a different blend that correlated with the eight different individuals. This indicated that the flies react different to different genetic makeup. They did not identify the particular pheromones that were in the blends produced.

In the second experiment, both vials contained six virgin females. I think that the genetically different flies reacted more vigorously to the females in an attempt to pass on their genes, making it a competition between the different flies to produce more viable offspring with better genes.

The article did not specifically say whether or not the genetically identical flies competed with each other for mates, but I would assume there would be some competition, just not as much as with the other group. Since they all are of pretty much the same genes, the drive to become the “top dog” is greatly reduced, I would suspect, because the offspring of all would be genetically very similar to each other. None would have an advantage of passing on better or more adaptive traits, because they all have mostly the same genes and traits. So in a way they may be willing to sacrifice a little.

A flaw to this experiment was the fact that they were only focusing on the reaction of the males. The females in the vials were just part of the experiment, and nothing was done to see if the females preferred one type over another, but perhaps in the fly world, females have no say? They did not give a reason for the female flies being virgins, but perhaps virgins are more attractive than non-virgins. Or perhaps they live only long enough to mate once? It is a bit inconclusive in that aspect.

I did not come across any other animals that have similar social behaviors to humans, but I am sure there is plenty out there. Like you said with the introduction of a new pet or a new sibling, it’s usually a similar reaction. I would be very surprise if there were not other animals that had similar social behaviors like humans.

Posted by: Katie Cole

At 10:15 PM, Anonymous Alicia Stein said...

I find it is a very bold statement to say we are just like fruit flies in social behavior, but I am continually surprised by the similarities between genetically complex species like humans and simpler organisms like fruit flies. I think such mating behaviors and social interactions listed in the article extend to most animals, it is surprising how behaviors we interpret as innately human can appear even more strongly in other species. For example, love birds, wolves, beavers, and several other animals mate for life. In human society, with a 50% divorce rate, such attachment is an accomplishment, if not a rarity. Is our genetic complexity creating better social interactions or just making them more complicated?


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