Who is he and what is he to you? Recognition in Drosophila melanogaster.

The inability to discriminate friend from foe or the 'one' among many potential mates can have immediate life-threatening consequences or a long-term evolutionary impact. Successful social interactions depend on the ability to recognize and identify individuals within a social context. Once recognition occurs, a repertoire of behavioral responses becomes available and choices are made as interactions between individuals unfold. The vinegar fly, Drosophila melanogaster, displays a wide range of social activities and patterns of social interaction. If a male fly is unable to recognize other males or distinguish them from females, he may attempt to court both males and females alike, wasting energy and reducing his fitness. We review recent studies on the mechanisms of social recognition in this organism that pertain to both sides of an interaction: the generation of signals by one individual and the receiving and processing of these signals by others.