Flexibility of collective decision making during house hunting in Temnothorax ants

Abstract

Many social animals cooperatively process information during decision making, allowing them to concentrate on the best of several options. However, positive feedback created by information sharing can also lock the group into a suboptimal outcome if option quality changes over time. This creates a trade-off between consensus and flexibility, whose resolution depends on the information-sharing mechanisms groups employ. We investigated the influence of communication behavior on decision flexibility in nest site choice by colonies of the ant Temnothorax rugatulus. These ants divide their emigration into two distinct phases separated by a quorum rule. In the first phase, scouts recruit nestmates to promising sites using the slow method of tandem running. Once a site's population surpasses a quorum, they switch to the faster method of social transport. We gave colonies a choice between two sites of different quality, and then switched site quality at different points during the emigration. Before the quorum was met, colonies were able to switch their choice to the newly superior site, but once they began to transport, their flexibility dropped significantly. Close observation of single ants revealed that transporters were more likely than tandem leaders to continue recruiting to a site even after its quality was diminished. That is, tandem leaders continued to monitor the quality of the site, while transporters instead fully committed to the site without further assessment. We discuss how this change in commitment with quorum attainment may enhance the rapid achievement of consensus needed for nest site selection, but at a cost in flexibility once the quorum is met.

Symmetry breaking and pivotal individuals during the reunification of ant colonies

“…Balsa slats were discarded after each experiment, but slides were re-used after cleaning in a commercial dishwasher. See Sasaki et al (2015) for further details on nest construction.…”

The Ecology of Collective Behavior in Ants

“…When a threshold density or so-called quorum is reached, the ants at the new nest site go back to the home nest and recruit other ants to the new one. In some species, the decision to choose a particular nest is also influenced by pheromone cues (114).…”

Temnothorax albipennis migration inspired semi-flocking control for mobile sensor networks

“…Much of these successes depend on their highly self-organized structures, efficient communication mechanisms, and effective division of labor 21 . One successful example of such group-living animals is a rock ant species known as T.albipennis 21,22 . Colonies of these ants build nests in rock crevices and frequently emigrate after the deterioration or destruction of their fragile nests.…”