Who directs group movement? Leader effort versus follower preference in stickleback fish of different personality

Abstract

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.

Guppies prefer to follow large (robot) leaders irrespective of own size

“…Also, we found no evidence that follower’s risk-taking behavior affected their tendencies to follow differentially-sized leaders. This result is in contrast to studies on sticklebacks where shyer individuals are better followers and are less likely to initiate leading themselves [8]. Besides possible species-specific differences, we argue that reinforcing feedbacks due to mutual influences among live animals may have led to the observed personality-dependent following behavior in sticklebacks [8, 34].…”

“…Often, occupation of front or peripheral positions is related to motivational or phenotypical differences among individuals [2, 5]. For example, individuals that go front are hungrier [6, 7], more risk-taking (‘bolder’) [4, 8–11] or simply larger [5, 12] than the rest of the shoal. Mechanistically, those individuals at front may swim faster [4, 12] or have larger repulsion areas [5, 13], both leading to an assortment within the shoal.…”

“…Using the golden shiner ( Notemigonus crysoleucas ), Reebs ([14]) showed that a minority of informed large fish was capable of leading a shoal of small fish to a food location but informed small fish had much lower success in leading a shoal of large fish even when occupying the front positions in the shoal. Furthermore, when sticklebacks ( Gasterosteus aculeatus ) were grouped with two partners of different personalities, they were more likely to follow the partner of similar personality out of cover [8]. Thus, both body size as well as behavior may determine leadership success in fishes.…”

Using a robotic fish to investigate individual differences in social responsiveness in the guppy

“…The use of live conspecifics for this purpose typically is problematic as they often interact with the focal individual and thereby introduce confounding variation into the experimental design (see e.g. [12-15]). Thus, experimenters tried to control for or standardize the possible mutual interactions among subjects.…”

Social dynamics, network structure, and information diffusion in fish shoals.

“…Conversely, there was little support for the bold-leader networks or disassortative mixing in shydominated and mixed groups. This may suggest that group personality composition affects the adoption of social roles during collective behaviors and/or the extent to which key individuals-such as informed group mates-can drive collective outcomes (Modlmeier, Keiser, et al, 2014;Nakayama et al, 2016).…”