Key individuals and the organisation of labor in ants.

In this chapter we examine the organisation of group behaviour at the level of the individual, and discuss the extent and significance of individual behavioural specialisation to group success. Studies of ants in which the behaviour of individuals as well as the group is recorded often reveal a high degree of individual specialisation in the absence of either age or morphological caste differences. Typically referred to as examples of elitism, idiosyncracy or specialisation, we incorporate these examples into a new classification, the key individual concept. This concept defines specialised individuals on the basis of their functional relationship to the behaviour of the group as a whole and indicates that a number of different organisational principles can underlie group behaviour. Some key individuals (catalysts) act to increase the activity level of other group members, whereas other key individuals (organisers) serve to ensure group cohesion and task completion. The demonstration that even large-scale process such as nest emigration can be organised by a subgroup of highly active individuals suggests that studies of group action might benefit from simultaneous analysis at both the individual and group level. Individuals may not always be behaviourally interchangeable, and individual behavioural specialisation, in the absence of age or caste differences, can be a significant component of group organisation.