Ants work harder during consensus decision-making in small groups

Abstract

Individuals derive many benefits from being social, one of which is improved accuracy of decision-making, the so-called 'wisdom of the crowds' effect. This advantage arises because larger groups can pool information from more individuals. At present, limited empirical data indicate that larger groups outperform smaller ones during consensus decision-making in human and non-human animals. Inaccurate decisions can lead to significant costs, and we might therefore expect individuals in small groups to employ mechanisms to compensate for the lack of numbers. Small groups may be able to maintain decision accuracy if individuals are better informed than those in larger groups and/or by increasing the proportion of the group involved in collective decision-making relative to larger groups. In this study, we use interactive computer vision software to investigate individual contributions to consensus decision-making during house-hunting in different sized groups of the ant Myrmecina nipponica. We show that individuals in small colonies invest greater effort in the consensus decision process than those in large colonies and should be better informed as a result. This may act to ameliorate the limitations of group size, but could leave smaller groups more susceptible to additional stresses.

Individual and Group Personalities Characterise Consensus Decision‐Making in an Ant

“…3b), although these factors were also linked. As in previous studies (Cronin 2014;Cronin & Stumpe 2014), quorum thresholds were higher in larger colonies (Table 2). There was also a colony size effect on the proportion of active ants, with the one smaller colony (B) having a notably higher proportion of active ants (Fig.…”

“…Intracolony heterogeneity in behaviour ('division of labour') is well known in social insects and is usually linked with genetic composition, size or age structure of colonies (H€ olldobler & Wilson 1990;Jeanson & Weidenm€ uller 2014). However, while colony size is known to influence collective processes in M. nipponica (Cronin 2014;Cronin & Stumpe 2014), colonies in this study were in most cases of similar size and, where different, did not vary in a manner consistent with a colony size effect (for example, the largest and smallest colonies exhibited the most similarity in performance characteristics). Similarly, this species is monogynous and monandrous (Murakami et al 2000), and thus variation between individuals is unlikely to have a genetic basis.…”

Emergent oscillations assist obstacle negotiation during ant cooperative transport

“…This result provides strong supporting evidence for this model and its assumptions. Importantly, it implies that the cooperative motion is not a wisdom-of-the-crowds phenomenon (25) in which the forces of a large number of poorly informed ants average out to increase overall accuracy (26,27). Such averaging behavior could result in fluctuations of the load around the direction to the nest (SI Appendix, Fig.…”

Flexibility of collective decision making during house hunting in Temnothorax ants

“…Because migration stage is a categorical variable, we recoded it as a series of dummy variables so that it could be included in regression analysis. We also tested whether accuracy was influenced by colony size, measured as number of workers, number of brood items, total colony population, and the ratio of brood to workers, as previous research has shown that these factors can influence decision making (Donaldson-Matasci and DeGrandi-Hoffman 2013; Schaerf et al 2013;Cronin and Stumpe 2014). Each colony size variable was included in the model to determine if it provided any additional predictive value compared with the model with migration stage only, and if not, it was removed from the model.…”