The Emergence of a Collective Threshold in the Response of Colonies of Clonal Raider Ants to Temperature Perturbations

The sensory threshold is one of the most fundamental and well studied computational primitives organisms perform, both as a standalone computation, and as a component of more complex tasks. In social organisms such as bee swarms and ant colonies, which perform computational tasks at the group level, the collective sensory threshold is an emergent property that depends on the responses of individuals in the group and on the interactions between them. Here we study this emergence in the clonal raider ant (Ooceraea biroi), a model system that provides convenient and precise control over the properties of the colony. We show that an ant colony indeed responds collectively to step changes in temperature, and that this response is characterised by a threshold. We further show that this threshold is sensitive to the size of the colony, implying that interactions play an important role. We then replicate the observed size dependency in a mathematical model, and show that it entails a change resisting interaction between the ants. Finally, we discuss how heterogeneity and variability between individuals in the group affect this emergence both in the model and in the experiment.