Loose social organisation of AB strain zebrafish groups in a two-patch environment.

Axel Séguret,José Halloy,Bertrand Collignon,Léo Cazenille,Yohann Chemtob,Stephan C.F Neuhauss

doi:10.1371/journal.pone.0206193

Axel Séguret, José Halloy + Show 4 more

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https://doi.org/10.1371/journal.pone.0206193

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Abstract

We study the collective behaviour of zebrafish shoals of different numbers of individuals (1, 2, 3, 5, 7, 10 and 20 AB zebrafish Danio rerio) in a constraint environment composed of two identical square rooms connected by a corridor. This simple set-up is similar to a natural patchy environment. We track the positions and the identities of the fish and compute the metrics at the group and at the individual levels. First, we show that the number of fish affects the behaviour of each individual in a group, the cohesion of the groups, the preferential interactions and the transition dynamics between the two rooms. Second, during collective departures, we show that the rankings of exit correspond to the topological organisations of the fish prior to their collective departure. This spatial organisation appears in the group a few seconds before a collective departure. These results provide new evidences on the spatial organisation of the groups and the effect of the number of fish on individual and collective behaviours in a patchy environment.

Highlights

We study the collective behaviour of zebrafish shoals of different numbers of individuals (1, 2, 3, 5, 7, 10 and 20 AB zebrafish Danio rerio) in a constraint environment composed of two identical square rooms connected by a corridor
Across the collective behaviours observed in social animals, collective movements [1,2,3,4,5,6,7,8], nest site selections [9,10,11,12] and site transitions [13] have been evidenced in many species
Numerous animal species have been observed in different sorts of constraint setups or mazes to study collective movements from one site to another: corridor type [3, 16, 21], Ymaze [22], T-maze [23] or Plus-maze [24, 25]. Such constraint set-ups engage the animals to transit alone or in group from site to site and allow the observation of leadership [26,27,28], initiation of group movements [19, 26, 29], followers organisations [26], pre-departure behaviours [19, 27] and sites transitions [13, 30, 31]. In these latter cases the authors studied the transitions from one site to the other of one and two fish separated by a transparent partition (Gasterosteus aculeatus and Sciaenops ocellatus)

Summary

Introduction

Across the collective behaviours observed in social animals, collective movements [1,2,3,4,5,6,7,8], nest site selections [9,10,11,12] and site transitions [13] have been evidenced in many species. Such constraint set-ups engage the animals to transit alone or in group from site to site and allow the observation of leadership [26,27,28], initiation of group movements [19, 26, 29], followers organisations [26], pre-departure behaviours [19, 27] and sites transitions [13, 30, 31] In these latter cases the authors studied the transitions from one site to the other of one and two fish separated by a transparent partition (Gasterosteus aculeatus and Sciaenops ocellatus). Such experimental procedure provided evidence of different leader/follower behaviours in fish, they prevent the fish from direct interactions between each other during the departures

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