Evolutionary ecology of communication signals that induce aggregative behaviour

Communication signals inducing aggregative behaviour profoundly affect a variety of ecological interactions, partly because they can be exploited by every member of the foodweb. To develop an evolutionary argument for the use of signals inducing aggregative behaviour in animals, the intricate role of aggregation pheromones in the ecology of Drosophila is discussed as a case study. Costs and benefits for the use of aggregation pheromone depend largely on the local characteristics of the environment, they involve various multitrophic interactions, and payoffs and penalties are density dependent. Plasticity in the use of pheromone is predicted and indeed found. For every ecological system, informational cues accompany food web interactions, and this affects the optimal strategy for individuals in their release of and response to such cues.