Competitive interactions in Drosophila melanogaster: genetic variation for interference through media conditioning

Interference, which is one of two aspects of the process of competition which take place in genetically heterogeneous mixtures has been studied in the Texas population of Drosophila melanogaster. Both survival and mean adult weight were investigated in the population itself (which displays high levels of aggression and little response) and in LA, a genotype derived from the population (which displays low aggression and high levels of response) in both homotypically and heterotypically conditioned media. The results presented here show that the competitive effects of conditioning depend not only on the concentration of the conditioned medium but also on the genotype of the larvae which conditioned the medium and that of the flies which respond to such media. It was also concluded that medium conditioning is one of a range of biological parameters involved in the determination of the aggression and response components of the competitive interaction among Drosophila larvae. Thus the competitive fitness of a genotype of D. melanogaster is related not only to genetic variation for aggression and response but also to genetic variation in the ability to condition media and the sensitivity to such media.