Testing the limits of social resilience in ant colonies

Social resilience is the ability of Leptothorax ant colonies to re-assemble after dissociation, as caused, for example, by an emigration to a new nest site. Through social resilience individual workers re-adopt their spatial positions relative to one another and resume their tasks without any time b eing wasted in worker re-specialisation. Social resilience can explain how an efficient division of labour can be maintained throughout the trials and tribulations of colony ontogeny including the, often substantial, period a fter the queen dies when the ability to conserve worker social relationship s may be essential for efficiency to be maintained. The mechanism underlyin g social resilience is, therefore, expected to be robust even in the absenc e of many of the colony's components, such as the queen, the brood and even a large proportion of the workers. Such losses are likely, given the ecolo gy of this genus. Using sociotomy experiments, we found that social resilie nce can occur in the absence of the queen. Furthermore, the spatial compone nt of social resilience can occur even when the queen, the brood, as well a s a large proportion of the workers, are all absent simultaneously and henc e many of the tasks are missing. We conclude, therefore, that social resili ence is indeed robust. This does not, however, preclude worker flexibility in response to changes in task supply and demand. We propose a possible sor ting mechanism based on worker mobility levels which might explain the robu stness underlying this phenomenon.