Data from: Who directs group movement? Leader effort vs follower preference in stickleback fish of different personality

During collective movement, bolder individuals often emerge as leaders. Here, we investigate whether this reflects a greater propensity of bold individuals to initiate movement, or a preference for shy individuals to follow a bolder leader. We set up trios of stickleback fish comprising a focal individual who was either bold or shy, and one other individual of each personality. We then recorded the movements of all individuals in and out of cover in a foraging context to determine how assiduously the focal fish followed the movements of each other partner. We found that a shy focal fish preferred to follow a leader whose personality matched its own, but we did not detect such a difference in bold fish. Despite this preference, however, the greater propensity of bold individuals to initiate movements out of cover meant that they successfully led more joint trips. Thus, when offered a choice of leaders, sticklebacks prefer to follow individuals whose personality matches their own, but bolder individuals may, nevertheless, be able to impose their leadership, even among shy followers, simply through greater effort.

在群体移动过程中，更大胆的个体往往会成为群体领导者。本研究旨在探究该现象背后的两种潜在机制：一是大胆个体本身更倾向于发起移动，二是害羞个体更偏好跟随大胆的领导者。我们以棘鱼（stickleback）为实验对象，设置了由三只个体组成的实验组：其中一只为焦点个体，其性格为大胆或害羞，另外两只分别对应这两种性格。随后，我们在觅食情境下记录了所有个体进出遮蔽区的移动行为，以此量化焦点鱼跟随其他伙伴移动的紧密程度。实验结果表明，性格害羞的焦点个体更倾向于跟随与自身性格匹配的领导者，但在大胆的焦点个体中并未观察到此类偏好差异。尽管存在上述性格匹配偏好，大胆个体更易主动发起离开遮蔽区的移动，这使得它们能够主导更多的群体联合移动。由此可见，当存在多个领导者选择时，棘鱼更偏好跟随与自身性格匹配的个体；但即便在害羞的跟随者群体中，大胆个体仍可凭借更高的行动积极性，强行确立自身的领导地位。