Data from: Conformity in the collective: differences in hunger affect individual and group behaviour in fish
Wilson, Alexander et al. (2019), Data from: Conformity in the collective: differences in hunger affect individual and group behaviour in fish, Dryad, Dataset, https://doi.org/10.5061/dryad.2dr683g
Animal groups are often composed of individuals that vary according to behavioural, morphological and internal state parameters. Understanding the importance of such individual-level heterogeneity to the establishment and maintenance of coherent group responses is of fundamental interest in collective behaviour. We examined the influence of hunger on the individual and collective behaviour of groups of shoaling fish, x-ray tetras (Pristella maxillaris). Fish were assigned to one of two nutritional states, satiated or hungry, and then allocated to 5 treatments that represented different ratios of satiated to hungry individuals (8 hungry, 8 satiated, 4:4 hungry: satiated, 2:6 hungry: satiated, 6:2 hungry: satiated). Our data show that groups with a greater proportion of hungry fish swam faster and exhibited greater nearest-neighbour distances. Within groups, however, there was no difference in the swimming speeds of hungry versus well-fed fish, suggesting that group members conform and adapt their swimming speed according to the overall composition of the group. We also found significant differences in mean group transfer entropy, suggesting stronger patterns of information flow in groups comprising all, or a majority of, hungry individuals. In contrast, we did not observe differences in polarization, a measure of group coherence, within groups across treatments. Taken together these results demonstrate that the nutritional state of animals within social groups impacts both individual and group behaviour, and that members of heterogenous groups can adapt their behaviour to facilitate coherent collective motion.