Self-organization mechanisms in ant societies (I):Trail recruitment to newly discovered food sources

Abstract

Behavioral patterns at the level of the society emerge spontaneously from the interactions between the individual ants. This process is comparable to the self-organization described in physico-chemical systems, in which both non-linear mechanisms and stochastic events play an essential role, and is illustrated by the way in which Tetramorium caespitum foragers are able to select one source from two offered in experimental conditions. The recruits spontaneously move towards the most efficient distribution between the two sources, within the limits of mass recruitment. The observed asymmetrical exploitation of two identical sources is described as a bifurcation phenomenon, and could not be explained by a traditional reductionist analysis of communication. It is predicted and explained, however, by a mathematical model which quantifies trail recruitment. In this model, error during trail following allows the discovery of a second source, and the increase in trail following accuracy as the recruitment proceeds is fundamental to the self-organization process, in this case the selection of one food source.