Cavity geometry shapes overall ant colony organization through spatial limits, but workers maintain fidelity zones

Many animals inhabit nests that protect them from adverse environments. However, the effects of living in a built or found structure are not limited to protection: the physical space can shape and organize behaviour, particularly in self-organized collective systems. In addition, the geometry of nest space may not be under the animal's control, raising the question whether animals can compensate for the effects that unexpected or suboptimal geometries may have. Here we examine how the shape of a nest cavity affects spatial organization of colonies in the ant Temnothorax rugatulus, a species that adapted to nest cavities of unmodifiable internal dimensions, since they inhabit rock crevices with rigid walls. We show that the emerging spatial relationships of workers, brood, queens and young alates, as well as their relationships and distances to significant points in the nest, are all significantly influenced by nest shape, with the brood distributions most affected. However, we also found that the size of worker spatial fidelity zones, i.e. the areas in the nest that individual workers occupy and that may be key regulators of division of labour, are overall not affected by nest shape. These findings indicate that ants may actively regulate which areas of a nest they occupy and that they may compensate for effects of nest architecture constraints. Physical properties of nests can thus influence the organization of ant colonies, highlighting the need to explore spatial constraints as a direct influence on the organization, movement and communication of evolved or engineered self-organized systems.