Abstract:
Attempts to account for observed variation in the degree
of reproductive skew among cooperative breeders have usually assumed
that subordinate breeding has fitness costs to dominant females.
They argue that dominant females concede reproductive opportunities
to subordinates to retain them in the group or to dissuade
them from challenging for the dominant position or that subordinate
females breed where dominants are incapable of controlling them.
However, an alternative possibility is that suppressing subordinate
reproduction has substantive costs to the fitness of dominant females
and that variation in these costs generates differences in the net
benefits of suppression to dominants which are responsible for variation
in the frequency of subordinate breeding that is not a consequence
of either reproductive concessions or limitations in dominant
control. Here, we show that, in wild Kalahari meerkats (Suricata
suricatta), the frequency with which dominants evict subordinates
or kill their pups varies with the costs and benefits to dominants of
suppressing subordinate breeding, including the dominants’ reproductive
status, the size of their group, and the relatedness of subordinates.
We review evidence from other studies that the suppression
of reproduction by subordinates varies with the likely costs of subordinate
breeding to dominants.
