Fruit Flies and Community Influence

Initially, I believed that fruit flies, like any other readily used lab insect, were very simple beings. I thought that their only intentions while they lived were to eat and survive long enough to reproduce and pass on their genes. I never would have thought that fruit flies would have had any social behaviors at all within the species. I actually thought they're whole lives were just fixed, but I was certainly wrong.

Recent studies dealing with fruit flies consisted in the observation of a single fruit fly's behavior isolated from any other fruit flies and then its introduction to a group of fruit flies. Apparently not only the behavior of the fruit fly changed within the first day of group introduction, but also the physiology and, even more interestingly- gene expression. This reminded me of the situation of the House Sparrows that I learned about in my animal behavior class. In the case of the house sparrow, when a male is around other males, that male may be treated differently in accordance to the size of the black chest badge he bears. In being treated differently, the male sparrow may produce more testosterone (if his chest badge is on the 'larger' side of the population's badges) due solely to an environmental cue.

One experiment done with the fruit flies consisted of observing flies similar at the genetic level in a group as opposed to flies variant at the genetic level. The results showed different chemical signals from the fruit flies in the genetically similar group than from the genetically different group. This experiment strongly supports the change in gene expression of a species due to an environmental/social cue.

Further observation of the fruit flies showed that the flies in the more genetically mixed groups mated and reproduced more than the fruit flies in the genetically similar groups. This gives more information about the sexual behavior of the fruit flies and could lead us to believe that the fruit flies may be interested in varying the diversity of their genes by mating with a partner of unalike features. In addition to the discovery of the increased sexual activity, the experiments performed displayed that the response of an individual male to fruit flies similar to himself depends on his neighbors- the other flies also present at the situation. The response, including chemical response (release of pheromones) given by that male fly was dependent on the peer's of the male fly, and therefore we can conclude that behavior is not only dependent on molecular signals, but also an element that contributes to the control of chemical signaling.



-Kiel Boutelle
-Bio 550 Section 1