Neural Mechanisms of Dominance Hierarchies in Crayfish

Abstract

The behavior of animals changes when they form a dominance hierarchy, and the change depends on the position they adopt in the hierarchy (Moynihan 1998). This chapter considers the relationship between the changes in the behavior of crayfish that accompany formation of a dominance hierarchy and the underlying change in the neural circuitry which mediates that behavior. During formation of a dominance hierarchy, two previously unacquainted animals meet and decide through mutual interaction which will have greater access to available resources now and in the future. Although their behavior may have been quite similar before their meeting, shortly afterwards it is not: one initiates nearly all agonistic encounters with attacks on the other, which escapes from these assaults with a rapid tailflip. Two weeks later, the level of aggression is much less, and both attacks and escapes are infrequent as the subordinate actively avoids the dominant. What accounts for this change in behavior? How does the nervous system change during these 2 weeks to produce very different behavior patterns in dominant and subordinate animals?