Reliability theory and foraging by ants

Reliability theory is used to explore the consequences of ant colony's foraging techniques for the evolution of individual competence. Five fundamental strategies are outlined according to Oster & Wilson (1978) and corresponding probabilities of food being returned to the nest are derived. The strategies differ in redundancy schemes and levels of worker reliability. Colony-level selection produces workers of imperfect competence. System reliability can be very high even when the workers are inept, if the foraging strategy is complex and redundant. Individual competence of foragers in a colony depends on diet breadth, caste polymorphism, and tempo. The implications of each variable for colony survival are discussed.