Differentiating among alternative models for the resolution of parentoffspring conflict

Understanding the behavioral mechanisms mediating the resolution of parentoffspring conflict is an important challenge given that the resolution of this conflict shapes the transfer of resources from parents to offspring. Three alternative models suggest that offspring begging provides an important behavioral mechanism for conflict resolution: honest signaling, scramble competition, and cost-free signaling models. However, there has so far been little progress in testing between these models because they share the same predictions. Here, we test between these models by focusing on their contrasting assumptions concerning who controls resource allocation and whether begging is costly in 2 experiments conducted on the burying beetle Nicrophorus vespilloides. In Experiment 1, we manipulated the degree to which offspring and parents can control resource allocation by presenting broods with age-based competitive asymmetries with a live or a dead female parent. We found that seniors (i.e., older larvae) gained more access to the parents mouthparts than juniors only when presented with a live parent. In Experiment 2, we provided parents with broods of 60 newly hatched larvae and found that larvae were more likely to become a target of filial cannibalism when begging than would be expected if parents targeted larvae irrespective of their behavior. These findings suggest that offspring begging increases the parents influence over food allocation and that begging is costly by increasing the offsprings risk of being a target of filial cannibalism. Our results support the assumptions of honest signaling models for the resolution of parentoffspring conflict.