Nest shape does not affect ant colony performance against a nest invader

Abstract

The spatial configuration or ‘architecture’ of an animal’s home can significantly affect the behavior of the occupant. However, the geometry of the occupied space may only partly be under the animals’ control, especially if pre-existing structures are used. In social animals in particular, such geometry may affect not only movement of individuals but also facilitate (or negate) cooperative interactions. How then does nest architecture translate to performance and fitness? We address this question by manipulating internal nest shape in a social insect, the ant Temnothorax rugatulus. We test the defensive performance of ant colonies against a conspecific nest invader in two distinct nest shapes, where nest invasion risks brood or queen loss. We also compared both worker movement and interaction networks in each nest shape to infer the spread of information about a nest invader. We specifically test the following hypotheses regarding how nest shape may affect performance (1) by changing how well information flows through each nest shape; (2) by changing the physical accessibility of different sections of the nest, including causing ’traffic jams’, i.e., total movement blocks; or whether, alternatively, (3) nest shape does not impact performance against nest invaders. We found that, while nest shape did affect information flow and traffic jams through the nest, performance itself (time to remove the invader) was not affected by nest geometry. Our findings imply that social animals may be able to flexibly adapt to, and possibly compensate for, different spatial constraints.