Group phenotypic composition drives task performances in ants

Abstract

Differences in individual behaviour within a group can give rise to functional dissimilarities between groups, particularly in social animals. However, how individual behavioural phenotypes translate into the group phenotype remains unclear. Here, we investigate whether individual behavioural type affects group performance in a eusocial species, the ant Aphaenogaster senilis. We measured individual behavioural traits and created groups of workers with similar behavioural type, either high-exploratory or low-exploratory workers. We tested these groups in four different, ecologically relevant, tasks: reaction to an intruder, prey retrieval from a maze, nest relocation and tool use. We show that, compared to groups of low-exploratory workers, groups of high-exploratory workers were more aggressive towards intruders, more efficient in collecting prey, faster in nest relocation and more likely to perform tool use. Our results demonstrate a strong link between individual and collective behaviour in ants. This supports the 'behavioural type hypothesis' for group dynamics, which suggests that an individual's behaviour in a social environment reflects its own behavioural type. The average behavioural phenotype of a group can therefore be predicted from the behavioural types of individual group members.

Keywords: animal personality; collective behaviour; exploratory activity; social insects.

Figure 1.

Tool use and reaction to intruder. (a) Latency of the first interaction with the honey bait. (b) Latency of the first interaction with a tool. (c) Stacked bars show the proportion of time of antennation (light green), mandible opening (orange) and biting (red). (d) Total time interacting with the intruder. High-exploratory sub-colonies are represented in green; low-exploratory sub-colonies in blue. Dots correspond to the latency of one sub-colony. Box plots show median (internal line), quartiles (box edges), min and max values, and outliers (filled dots outside whiskers).

Figure 2.

Prey retrieval and nest relocation. Latency of (a) first entrance into the maze, (b) first contact with a D. melanogaster, and (c) first fly transported into the nest (upper row). Latency of (d) first discovery of the new nest, (e) first brood transported into the nest. (f) Number of workers carrying brood (lower row). High-exploratory sub-colonies are shown in green; low-exploratory sub-colonies in blue. Dots correspond to the latency or to the number of workers carrying brood in one sub-colony. Box plots show median (internal line), quartiles (box edges), min and max values, and outliers (filled dots outside whiskers).