Social dominance, copulatory behavior, and differential reproduction in deer mice (Peromyscus maniculatus).

Abstract

Although it is generally believed that social dominance leads to increased levels of copulatory behavior and production of offspring, effects of dominance and copulatory behavior on measured reproductive success have rarely been determined. Three experiments were conducted with blonde and wild-type deer mice, P. maniculatus, in which dominance, copulatory behavior, and the production of offspring were measured. In all 3 experiments, in both short-term tests in small cages and long-term tests in large enclosures, dominant males completed more copulations than subordinates. This increased copulatory behavior resulted in no significant increase in differential reproduction in small cages and in increases of marginal statistical significance in large enclosures. Although copulatory behavior was minimally changed as a function of cage size, social interactions were more substantially changed. Caution is required when inferring differences in fitness from differences in rank and copulatory behavior.