Data for: Social rank and not physiological capacity determines competitive success in zebrafish (Danio rerio)

Competition for resources shapes ecological and evolutionary relationships. Physiological capacities such as in locomotor performance can influence the fitness of individuals by increasing competitive success. Social hierarchy too can affect outcomes of competition by altering locomotor behaviour or because higher-ranking individuals monopolise resources. Here we tested the alternative hypotheses that competitive success is determined by sprint performance or by social status. We show that sprint performance of individuals measured during escape responses (fast start) or in an accelerated sprint test did not correlate with realised sprint speed while competing for food within a social group of five fish; fast start and accelerated sprint speed were higher than realised speed. Social status within the group was the best predictor of competitive success, followed by realised speed. Social hierarchies in zebrafish are established within seven days and, interestingly, there was a positive correlation between social status and realised speed one and four days after fish were placed in a group, but not after seven days. These data indicate that physiological performance decreases in importance as social relationships are established. Also, maximal physiological capacities were not important for competitive success, but swimming speed changed with social context.