I've just finished a news story for Laboratory News. I thought that SNAB students would particularly like it. It seems that the little fly (of all of the genetics experiments) is an aggressive chap. The males of the species are able to detect pheromones (chemicals) and when the pheromones rise, so too does the aggression and the ability to fight other males. What this means is that when a group of males get together to feed, the more males there are, the more likely they are to fight and chase each other off. Under laboratory conditions and when presented with the artificial pheromone, the male Drosophila will fight until one "top fly" remains. The biological advantage to this is that when there is limited food, the "top fly" will try to gain the selective advantage of bagging the food for himself and chasing away his opponents. The alpha male not only gets the food - he also gets the ladies too! As the other males slowly retreat, so the pheromone levels drop and the aggression disappears, and a quiet, happy life is restored in the Drosophila colony.