A Model of Subordinate Helping Decisions Under Varying Levels of Uncertainty

R Layne Gaynor, Ian M Hamilton. 2026. Behavioral Ecology, arag057, DOI: 10.1093/beheco/arag057.

Abstract

In many cooperative breeding societies subordinates pay-to-stay, providing help to dominants in order to avoid eviction. However, this requires that dominants be able accurately assess the help being provided to them. Ecological changes, including human-induced rapid environmental change, can alter dominants’ sensory environment, which may in turn alter subordinate behavior. Here, we developed a dynamic game model to examine how varying levels of dominant uncertainty impact subordinate helping policies. We then used these policies to examine subordinate fitness by simulating subordinate helping in sensory environments that either matched or did not match the environment under which a policy evolved. We found that dominant uncertainty about subordinate identity had size-specific effects on subordinate helping, whereas increased uncertainty about the amount of help being provided caused increased subordinate helping. This resulted in higher rates of subordinate eviction and mortality when uncertainty was high. Simulated mismatches between historic and current levels of uncertainty revealed that changes in dominants’ ability to assess the amount of help a subordinate provides had strong effects on subordinate fitness. Our results highlight the importance of the sensory environment in negotiations between cooperative individuals and how sudden changes in the sensory environment can impact subordinate fitness.