The effects of inbreeding on aggression in wild male house mice (Mus domesticus)

This study examined the effect of inbreeding on aggression levels and competitive ability in wild male house mice. Wild mice were bred in the laboratory to produce males of three levels of inbreeding: male offspring of unrelated parents, male offspring of first-cousin parents, and male offspring of full-sibling parents. Paired encounters were staged between males of the three offspring groups, when the males reached maturity. Less inbred males won more encounters and tended to have higher scores of aggression level than more inbred males. If competitive ability in the laboratory is related to competitive ability in nature, wild mice from this population may benefit from avoiding inbreeding and the consequent decrease in aggression levels and competitive ability.