Figure 3.

Time dynamics of male services and received payment. Males pay each time they participate in an between-group conflict (BGC; red arrows). They receive the benefits of group membership constantly (horizontal line). In addition, they may be rewarded with grooming each time they participate in a BGC (yellow arrows). Finally, males may also achieve copulations in return for their services, which would be rare events and linked to female fertility/a mating season rather than a specific own service.