| Description |
Social dominance is the most important known behavior to reproductive success of males across the animal kingdom. A high social dominance rank is usually gained by physical competition or signals displaying competitor quality. Despite its importance in shaping the diversity seen in the animal kingdom, little is known about specific traits that promote high competitive ability within an individual. In this dissertation, I begin to elucidate some of the behavioral physiology underpinning competitive ability in the premier mammalian model system, the house mice (Mus musculus). House mice are ideally suited for this study because of a well-characterized natural history demonstrating that dominant males gain ~90% of all fitness, while still having to perform many other behaviors, such as foraging. In this dissertation, I provide an overview of the some hypothesized constraints on the evolution of competitive ability and phenotypic trade-offs with other important life-history traits. Second, I describe an experiment that investigated multiple traits at several levels of biological for their possible influence on competitive ability. I demonstrate that competitive ability is heritable, moderately influenced by relative body mass, and negatively influence by litter sex ratio. No effect of litter size, relative age, or placement order was seen. Third, I demonstrate that aggression and competitive ability are distinct phenomena in iv this system. Next, I demonstrate that primary signaling pheromone of house mice, major urinary proteins, do not advertise rank but are responsive to social experience. Finally, I switch clades and demonstrate that relative brain size in primates is positively associated with intensity of male-male competition. Collectively, this project demonstrates that competitive ability is an extremely complicated phenotype and merits a great deal more study. |
