Graph theory in animal behavior and the social role of gatekeepers on group learning in zebrafish shoals, Danio rerio

Social behavior research has moved from a focus on dyads to considering larger group dynamics. Individual animals can adopt particular social roles in a group, such as "gatekeepers", who control information flow by interacting freely with other animals in the group. In my dissertation, I start with a computer simulation analysis to explore the performance of graph theory metrics to infer information flow in smaller social groups common of animal behavior. By varying different group attributes, we found that some metrics are better than others at describing certain aspects. I found that at least ten interactions should be recorded for each individual in a group. Additionally we make recommendations for specific combinations of metrics and I describe the performance of different metrics under different scenarios. In the experimental part of my dissertation, I looked at how gatekeepers influence the process of group dynamics, group performance and social learning in zebrafish groups. I worked with two different zebrafish strains; a lab reared and a recently derived wild strain. First I identified and removed gatekeepers or non-gatekeepers from different groups. Then I looked at the effect of removal on group dynamics and group learning performance. I found that social dynamics does have an impact on group learning: groups that retained their gatekeeper (removed non-gatekeeper) learned more quickly than did groups from which I had removed the gatekeeper. I found that different strains respond differently to the removal of individuals, suggesting a possible underlying genetic effect. In another set of experiments, I identified, removed and trained individual gatekeepers and non-gatekeepers, returned them to their initial social group, and then trained the entire group on a simple associative task. I found that gatekeepers do play a more important role on information transfer; groups with pre-trained gatekeepers learned more quickly than did groups with pre-trained non-gatekeeper. Finally I found that male tutors were better at transferring information regardless of their gatekeeper status. These results show that individual zebrafish take on specific roles within a social group, and confirm that those roles can impact group dynamics and learning ability.