Ant workers exhibit specialization and memory during raft formation
By working together, social insects achieve tasks that are beyond the reach of single individuals. A striking example of collective behaviour is self-assembly, a process in which individuals link their bodies together to form structures such as chains, ladders, walls or rafts. To get insight into how individual behavioural variation affects the formation of self-assemblages, we investigated the presence of task specialization and the role of past experience in the construction of ant rafts. We subjected groups of Formica selysi workers to two consecutive floods and monitored the position of individuals in rafts. Workers showed specialization in their positions when rafting, with the same individuals consistently occupying the top, middle, base or side position in the raft. The presence of brood modified workers’ position and raft shape. Surprisingly, workers’ experience in the first rafting trial with brood influenced their behaviour and raft shape in the subsequent trial without brood. Overall, this study sheds light on the importance of workers’ specialization and memory in the formation of self-assemblages.
KeywordsSelf-assemblage Collective behaviour Task specialization Rafting Ants Formicinae
We thank Magalie Dialundama for her assistance in the lab, Emilie Lefoulon for the illustration of the ant raft, and Christoph Grüter, Adam L. Cronin and anonymous reviewers for comments on the manuscript. This project was funded by Swiss National Science Foundation grant 31003A-146641.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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