Information and Motivation Interact to Determine Leadership in Schools of Golden Shiners (Notemigonus crysoleucas)

Abstract

In numerous animal groups, individuals within the group often wish to impose their preferences and guide the group in a certain direction. Conflicting preferences are common in these situations and, in order to maintain group cohesion, collective decisionmaking needs to occur. To accomplish this, members of the group discern between multiple mutually exclusive behaviors to choose the behavior that would lead to the greatest fitness benefit. Due to the inherent complexity of this process, studies such as this one have attempted to uncover the mechanisms that guide collective decision-making in animal groups for quite some time. Researchers have noted that leadership plays a large role in collective decisionmaking, and multiple factors were found to have important roles in determining a leader including: physical size, personality, nutritional state, and knowledge of the location of a food source. In this study, we attempt to explore the possible relationship between two of the most important qualities that determine whether an individual will become a leader of a group: informational state and nutritional state. Using golden shiners, Notemigonus crysoleucas, we studied the collective decision-making that occurs when groups decide between two alternative channels in a Y-maze. We concentrated on two focal areas when conducting the experiment: an individual’s accuracy in making a decision and an individual’s rank in the group as they progressed through the maze. The experiment’s results were very suggestive of a few interesting phenomena. For individual accuracy, our data suggest a reduction in accuracy of informed individuals when they are paired with uninformed individuals. For individual rank, our data suggest a trend by which nutritional state is more influential in determining early leaders. However, as the group progresses through the maze, an overtaking behavior occurs by the informed individuals, thus causing informational state to become the primary factor in determining leadership late in the maze. Our results further reveal the complex dynamics involved in the decentralized determination of a leader, however more data are needed in order to establish significant results.