Unfavourable environment limits social conflictin Yuhina brunneiceps

摘要

Identifying the factors that modulate cooperative and competitive behaviours is the key tounderstanding social evolution. However, how ecological factors affect social conflict andtheir fitness consequences remain relatively unexplored. Here, using both a game-theoreticalmodel and empirical data, we show that Taiwan yuhinas (Yuhina brunneiceps)—a joint-nestingspecies in which group members are unrelated—employ more cooperative strategies inunfavourable environmental conditions. Fighting duration was lower, fewer total eggs were laidand incubation was more likely to start after all females completed egg laying (which causesmore synchronous egg hatching). surprisingly, as a consequence, there were more survivingoffspring in unfavourable conditions because the cooperative strategies resulted in fewer deadnestlings. To our knowledge, this study is the first theoretical analysis and empirical studydemonstrating that an unfavourable environment reduces social conflict and results in betterfitness consequences in social vertebrates.