arXiv subjects

Bertrand Collignon

Publications and source records attributed to Bertrand Collignon.

4 recordsLinked to original sources

arXiv2017

Collective departures in zebrafish: profiling the initiators

For animals living in groups, one of the important questions is to understand what are the decision-making mechanisms that lead to choosing a motion direction or leaving an area while preserving group cohesion. Here, we analyse the initiation of collective departure in zebrafish \textit{Danio rerio}. In particular, we observed groups of 2, 3, 5, 7 and 10 zebrafish swimming in a two resting sites arena and quantify the number of collective departure initiated by each fish. While all fish initiated at least one departure, the probability to be the first one to exit a resting site is not homogeneously distributed with some individuals leading more departures than others. We show that this number of initiation is linearly proportional to the number of attempts performed and that all fish have the same success rate to lead the group out of a resting sites after an attempt. In addition, by measuring the average swimming speed of all fish, we highlight that the intra-group ranking of a fish for its proportion of initiation is correlated to its intra-group ranking in average speed. These results highlight that the initiation of collective departure in zebrafish is a heterogeneously distributed process, even if all individual have the same success rate after attempting a departure.

q-bio.PE↗

arXiv2017

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

We explore the collective behaviours of 7 group sizes: 1, 2, 3, 5, 7, 10 and 20 AB zebrafish (Danio rerio) in a constraint environment composed of two identical squared 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 size of the population 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 with no leadership. This spatial organisation emerge 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 population size on individual and collective behaviours in a patchy environment.

q-bio.PE↗

arXiv2016

Strains differences in the collective behaviour of zebrafish (Danio rerio) in heterogeneous environment

Recent studies show differences in individual motion and shoaling tendency between strains of the same species. Here, we analyse the collective motion and the response to visual stimuli in two morphologically different strains (TL and AB) of zebrafish. For both strains, we observe 10 groups of 5 and 10 zebrafish swimming freely in a large experimental tank with two identical attractive landmarks (cylinders or disks) for one hour. We track the positions of the fish by an automated tracking method and compute several metrics at the group level. First, the probability of presence shows that both strains avoid free space and are more likely to swim in the vicinity of the walls of the tank and the attractive landmarks. Second, the analysis of landmarks occupancy shows that AB zebrafish are more present in their vicinity than TL zebrafish and that both strains regularly transit from one landmark to the other with no preference on the long duration. Finally, TL zebrafish show a higher cohesion than AB zebrafish. Thus, landmarks and duration of the repicates allow to reveal collective behavioural variabilities among different strains of zebrafish. These results provide a new insight into the need to take into account individual variability of zebrafish strains for studying collective behaviour.

q-bio.QM↗

arXiv2015

Zebrafish collective behaviour in heterogeneous environment modeled by a stochastic model based on visual perception

Collective motion is one of the most ubiquitous behaviours displayed by social organisms and has led to the development of numerous models. Recent advances in the understanding of sensory system and information processing by animals impel to revise classical assumptions made in decisional algorithms. In this context, we present a new model describing the three dimensional visual sensory system of fish that adjust their trajectory according to their perception field. Furthermore, we introduce a new stochastic process based on a probability distribution function to move in targeted directions rather than on a summation of influential vectors as it is classically assumed by most models. We show that this model can spontaneously transits from consensus to choice. In parallel, we present experimental results of zebrafish (alone or in group of 10) swimming in both homogeneous and heterogeneous environments. We use these experimental data to set the parameter values of our model and show that this perception-based approach can simulate the collective motion of species showing cohesive behaviour in heterogeneous environments. Finally, we discuss the advances of this multilayer model and its possible outcomes in biological, physical and robotic sciences.

physics.bio-ph↗