Ant larvae as players in social conflict: relatedness and individual identity mediate cannibalism intensity

Conflict arises among social organisms when individuals differ in their inclusive-fitness interests. Ant societies are excellent models for understanding how genetic relatedness mediates conflict intensity. However, although conflicts within colonies typically arise over offspring production, the role of larvae as actors in social conflict has received little attention. We develop and empirically test kin-selection theory of larval egg cannibalism in ant societies. Specifically, we investigate how selection for cannibalism is mediated by nestmate relatedness and larval sex in a mathematical model and then test the model’s predictions by measuring cannibalism levels in eight ant species with varying nestmate relatedness. In line with our theoretical predictions, cannibalism levels in larvae were significantly influenced by relatedness and sex. Increased relatedness was associated with reduced levels of cannibalism, indicating that larval behavior is mediated by inclusive-fitness consider...