Failures of reproductive suppression in dwarf mongooses (Helogale parvula): accident or adaptation?

Publisher Website
Google Scholar
Abstract
In many communally breeding species, only the dominant female normally breeds, while subordinates tolerate reproductive suppression (these are “despotic” species, in the terminology of Brown, 1987; Macdonald and Moehlman, 1983; Vehrencamp, 1983). Yet in many species for which reproductive suppression is the norm (across a wide variety of taxa), subordinates do occasionally breed. Because reproduction by subordinates is atypical for these species, it is often regarded as simple failure of the normal mechanisms of suppression. An alternate hypothesis is that subordinate pregnancies represent an evolutionary compromise between dominant and subordinate, in which dominants concede their monopoly on reproduction in order to retain helpers. We use data from a long-term study of dwarf mongooses (Helogale parvula) in Serengeti National Park, Tanzania, to test this hypothesis, using an inclusive fitness model adapted from one by Vehrencamp (1983). We find that the incidence of subordinate pregnancy closely matches that predicted by the model, suggesting that the mechanisms that underlie reproductive suppression in dwarf mongooses are finely adjusted to the social and demographic environment. [Behav Ecol 1991; 2: 7–15]