The Ecology of Collective Behavior

Like many biological systems, an ant colony operates without central control. Each ant responds to its interactions with other ants nearby. In the aggregate, these stochastic, dynamical networks of interaction regulate colony behavior. Ants are extremely diverse, and species differences in collective behavior reflect relations with environments of diverse dynamcs. Some important aspects of the dynamics of the environment include its stability, the threat of rupture or disturbance, the ratio of inflow and outflow of resources or energy, and the distribution of resources. These correspond to the dynamics of collective behavior, including the rate of amplification, how feedback instigates and inhibits activity, and whether information is spatially centralized. An example is the contrast between the regulation of foraging by harvester ants in the desert, where water is limited but resources are stable. Colonies regulate foraging activity according to food availability and humidity, and natural selection is shaping collective behavior in response to drought conditions. For arboreal turtle ants in the tropical forest, activity is easier but conditions are unpredictable.  Their trail networks are maintained and repaired using a simple algorithm that allows colonies to respond to changing conditions.