Social uncertainty influences the optimal balance of quantity and quality of cooperative relationships

Raven Hartman , Gerald G Carter

Many group-living animals develop and maintain stable affiliative social relationships. These ‘social bonds’ can benefit survival and reproduction, but they require significant investments of time and energy. How should individuals allocate those investments towards building new relationships (“diversifying”) versus maintaining existing ones (“focusing”)? The ‘social bet-hedging’ hypothesis states that conditions of greater social certainty (more reliable partner availability) favour greater “focusing”, whereas conditions of social uncertainty favour “diversifying”. This hypothesis is consistent with empirical findings in vampire bats, yet support from agent-based models is mixed. Here, we used an agent-based model to test the relative reproductive success of different “social-networking strategies” in vampire bats under conditions of greater or lower social uncertainty. To manipulate social uncertainty, we minimized or maximized roost-switching rates across simulations with realistic patterns of foraging, social behaviour, ageing, reproduction, and death. Virtual bats inherited one of six social-networking strategies, which varied in allocation of allogrooming across partners, from more focusing to more diversifying. We show that, under a range of conditions, greater social uncertainty favours diversifying strategies that invest relatively more in relationship quantity. Balancing the benefits of focusing and diversifying attention across social partners may be an important yet underappreciated factor explaining social network structure.