From a cost-benefit point of view, we can expect a multi-male multi-female social unit to be stable if, and only if, the minimum value in copulation share requested by a subordinate male, defined as “Pmin”, is equal to or less than the maximum share granted by the dominant male, defined as “Pmax”, (Johnstone, 2000). A social unit will be defined as having a “high skew” when the dominant male monopolizes most of the copulations, while a “low skew” will be the result of a large share in copulations between the different males in the unit. The factors defining the copulation share may vary subordinates to remain in the social unit. In cases where the subordinate males receive less than a minimum share in reproduction, it will be best for them to depart the group and try to breed elsewhere. On the other hand, if the dominant male has to concede a higher share than is expected it will be best for him to evict
the subordinates (Vehrencamp, 1983; Johnstone & Cant, 1999; Johnstone, 2000)