Size distribution and battles in wood ants: group resource-holding potential is the sum of the individual parts

► In social animals such as wood ants, aggression takes place between rival groups. ► We investigated the effects of within-group variation in fighting ability. ► Large individuals were more aggressive and less likely to die. ► Mass-distribution within-groups had no effect on the overall outcome. ► Group fighting ability was driven by the individual fighting abilities of members.