Wendy Saltzman: UC Riverside Department of Biology

Common marmosets are cooperatively breeding monkeys that exhibit high female reproductive skew: typically only a single, dominant female breeds successfully in each social group. Laboratory studies have indicated that reproductive suppression in subordinate females is not aggressively imposed on them by dominant females and is not associated with stress; instead, it is mediated by a specific, presumably adaptive neuroendocrine mechanism. Moreover, subordinate females readily begin to breed under favorable conditions, such as following introduction of an unrelated male into the group, and show no impairments in their ability to maintain pregnancy or successfully produce offspring. When two females breed concurrently, however, they engage in overt reproductive competition, with pregnant females commonly killing one another’s infants. In sum, our findings are consistent with recent manipulation-based models of reproductive skew, in which reproductive suppression in non-breeders is mediated, mechanistically, by self-restraint but has evolved in response to selection – namely, infanticide – imposed by breeding females.
http://www.bec.ucla.edu/papers/Saltzman_1.22.07.pdf