Trade-offs between extraterritorial prospecting and helping in a cooperative mammal

Abstract

Males commonly face a trade-off between investment in offspring care and time spent seeking additional breeding opportunities. Although this trade-off is central to our understanding of the evolution of male parental care, it has been largely ignored by studies of male alloparental care in cooperative societies, where male helpers could face a similar problem. We investigated whether male helpers in cooperative societies of meerkats Suricata suricatta trade off their cooperative contributions to pup feeding against extraterritorial prospecting for mating and dispersal opportunities. Not only did male helpers spend extended periods away from the group during pup care periods, but those that spent most time prospecting also contributed least to pup feeding when present in the group. Regular prospectors lost the most weight over the pup-feeding period and male testosterone levels increased in association with prospecting. As both reduced body condition and elevated testosterone have been shown to compromise the expression of offspring care, these findings provide likely explanations for the reduced pup-feeding rates of regular prospectors. Despite their lapses in contributions to cooperative activities, we found no evidence for punishment of prospectors by other group members, suggesting that helpers are able to adjust their contributions according to their own optima. These findings reveal that male helpers in cooperative species can face similar trade-offs to male parents in noncooperative species, between investment in offspring care and alternative fitness-maximizing tactics such as prospecting. We discuss the broader implications of this work for our understanding of both individual variation and sex differences in contributions to cooperative behaviour.