Collective departures and leadership in zebrafish
Collective departures and leadership in zebrafish
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DOI：
10.1371/journal.pone.0216798
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发表时间：
2019-05-23
期刊：
影响因子：
3.7
通讯作者：
Halloy, Jose
中科院分区：
文献类型：
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作者：
Collignon, Bertrand;Seguret, Axel;Halloy, Jose
在社会性动物中，形态和行为特征可能会对某些个体的集体决策产生更大的影响，即使是在鱼群等被认为是无领导的群体中也是如此。在这里，我们通过观察 2、3、5、7 和 10 条斑马鱼在两个休息场所的竞技场中游泳一小时来研究和表征斑马鱼群集体运动的领导力。我们量化了每条鱼发起的集体离开的次数以及它们尝试的次数。为此，我们开发了一个自动化管道来分析跟踪软件生成的各个轨迹。对于所有大小的浅滩，领导权都分配给几个人。然而，一些浅滩中的所有鱼类均等地分享了集体离开的信息，而其他群体则表现出更加不对称的集体离开。为了量化这种分布，我们计算了与每个实验的所有发起者身份的时间序列相关的熵，并确认了领导力的同质和异质分布之间存在连续体。虽然有些鱼比其他鱼带领鱼群离开的次数更多，但一项单独的分析表明，所有鱼在尝试带领鱼群离开休息地点的成功率实际上是相同的。因此，一些人通过比其他人更频繁地尝试离开休息场所来垄断领导权。最后，我们强调，鱼的主动性的组内排名与其平均速度的组内排名相关，移动个体更容易领导浅滩。这些结果表明，即使鱼对其同类没有较高的影响，浅滩的集体行为也可以主要由一部分个体驱动。
In social animals, morphological and behavioural traits may give to some individuals a stronger influence on the collective decisions, even in groups assumed to be leaderless such as fish shoals. Here, we studied and characterized the leadership in collective movements of shoals of zebrafish Danio rerio by observing groups of 2, 3, 5, 7 and 10 zebrafish swimming in a two resting sites arena during one hour. We quantified the number of collective departures initiated by each fish and the number of attempts that they made. To do so, we developed an automated pipeline that analysed the individual trajectories generated by the tracking software. For all shoal sizes, the leadership was distributed among several individuals. However, it was equally shared among all the fish in some shoals while other groups showed a more asymmetrical sharing of the initiation of collective departures. To quantify this distribution, we computed the entropy associated with the time series of the identity of all initiators for each experiment and confirmed the presence of a continuum between a homogeneous and a heterogeneous distribution of the leadership. While some fish led more departures than others, an individual analysis showed that all fish had actually the same success rate to lead the shoal out of a resting site after an attempt. Thus, some individuals monopolized the leadership by attempting more often than others to exit a resting site. Finally, we highlight that the intra-group ranking of a fish for the initiative is correlated to its intra-group ranking for the average speed with mobile individuals more prone to lead the shoal. These results demonstrate that the collective behaviour of a shoal can be mainly driven by a subset of individuals even in the absence of higher influence of a fish on its congeneers.