Boldness Predicts Social Status in Zebrafish (Danio rerio)

S Josefin Dahlbom,David Lagman,Svante Winberg,L Fredrik Sundström,Katrin Lundstedt-Enkel,Gonzalo G De Polavieja

doi:10.1371/journal.pone.0023565

Abstract

This study explored if boldness could be used to predict social status. First, boldness was assessed by monitoring individual zebrafish behaviour in (1) an unfamiliar barren environment with no shelter (open field), (2) the same environment when a roof was introduced as a shelter, and (3) when the roof was removed and an unfamiliar object (Lego® brick) was introduced. Next, after a resting period of minimum one week, social status of the fish was determined in a dyadic contest and dominant/subordinate individuals were determined as the winner/loser of two consecutive contests. Multivariate data analyses showed that males were bolder than females and that the behaviours expressed by the fish during the boldness tests could be used to predict which fish would later become dominant and subordinate in the ensuing dyadic contest. We conclude that bold behaviour is positively correlated to dominance in zebrafish and that boldness is not solely a consequence of social dominance.

Highlights

All animals are faced with challenges that can be approached in mainly two ways, each defining a ‘coping style’
To investigate how stable the model was, we explored if shorter experimental time would be sufficient to calculate the actual social status, starting with the first period alone and the first two periods combined, comparing with the results when using all three periods
All subordinates still ate and the dominant fish did not defend the feed. In one case both fish swam freely throughout the entire tank but the dominant was still chasing the subordinate with a low frequency

Summary

Introduction

All animals are faced with challenges that can be approached in mainly two ways, each defining a ‘coping style’. Reactive animals respond to stress with higher activation of the hypothalamic-pituitary-adrenal (HPA)/interrenal (HPI, the interrenal being the teleostean homologue of the mammalian adrenal) axis, leading to higher post stress levels of glucocorticoids in reactive than proactive animals [1,3,4]. These coping styles have been found repeatedly in rodents [1,3,4] and fish, such as three-spined stickleback (Gasterosteus aculeatus) [5,6,7], brown trout (Salmo trutta) [8], Senegalese sole (Solea senegalensis) [9] and rainbow trout (Oncorhynchus mykiss) [10]. Reactive animals act passively towards threats, surviving by staying away from danger

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Conclusion