Data from: Experience and motivation shape leader-follower interactions in fish shoals

Leadership is an important process shaping collective movement in some species. Recent work has demonstrated that experienced or motivated individuals can emerge as leaders, and provides insight into the mechanisms by which this occurs. Ultimately, leadership depends upon the effectiveness with which would-be leaders can entrain followers, and while the properties of leaders have received much attention, less is known about the factors that affect the propensity of their groupmates to follow them. Here the roles of experience and state (hunger) in shaping leader and follower behavior were investigated using shoals of sticklebacks (Gasterosteus aculeatus). A first experiment revealed that individuals trained to approach a target could entrain and lead their naïve groupmates out of a refuge towards it, and that they did so more effectively when they (the trained fish) were food-deprived. In the second experiment the hunger level of the trained fish was held constant, while that of the naïve fish was varied. Here, leadership by trained fish was only apparent when the hunger levels of the naïve group members were intermediate. When naïve fish were recently fed they took a long time to visit the target and their arrival times were not affected by the presence of a trained individual. Very hungry groups recruited to the target most rapidly, but again with no evidence of influence by their trained groupmates. These experiments demonstrate that leadership in animal groups depends not only upon the state and experience of the leader but also upon that of the potential followers.

领导力是驱动部分物种形成集体运动模式的核心过程。既往研究表明，具备丰富经验或较高行动动机的个体可脱颖而出成为群体领导者，并为该现象背后的潜在作用机制提供了重要见解。归根结底，领导力的本质在于潜在领导者能否有效带动追随者同步行动；尽管学界已对领导者自身的特质展开了大量研究，但针对影响群体成员追随意愿的相关因素，目前仍所知有限。本研究以三刺棘鱼（Gasterosteus aculeatus）的鱼群为实验对象，探讨了个体经验与生理状态（饥饿程度）对领导者及追随者行为的调控作用。第一项实验结果显示，经过训练、可主动趋近目标区域的个体，能够带领未接受过训练的同伴逃离庇护所并前往目标区域；且当训练个体处于食物剥夺状态时，其带领效率会显著提升。第二项实验中，研究人员固定训练个体的饥饿水平，同时调整未受训个体的饥饿状态。结果表明，仅当未受训群体成员的饥饿程度处于中等水平时，训练个体的领导者身份才会显现。当未受训个体刚完成进食时，其抵达目标区域的耗时较长，且训练个体的存在并不会对其到达时间产生影响；而极度饥饿的群体虽能最快抵达目标区域，但同样未表现出受训练同伴的影响。上述实验证实，动物群体中的领导力不仅取决于领导者自身的生理状态与经验水平，同时也与潜在追随者的状态与经验密切相关。