Studies in Wild House Mice 3: Disruptive Selection on Aggression as a Possible Force in Evolution

In many animal species intraspecific aggressive behaviour has a powerful impact on the relative positions of the individuals in social structures. The status attained often affects the individual’s chances of survival and/or its chance to generate progeny, and thus expresses its relative fitness. Crowcroft 1 provided good examples of these phenomena in house mice. Such animals show large individual differences in aggressiveness, part of which is of genetic origin. This holds for both laboratory mice 2–3 and wild mice 4–6 .