Unfavourable environment limits social conflict in Yuhina brunneiceps.
Identifying the factors that modulate cooperative and competitive behaviours is the key to understanding social evolution. However, how ecological factors affect social conflict and their fitness consequences remain relatively unexplored. Here, using both a game-theoretical model and empirical data, we show that Taiwan yuhinas (Yuhina brunneiceps)--a joint-nesting species in which group members are unrelated--employ more cooperative strategies in unfavourable environmental conditions. Fighting duration was lower, fewer total eggs were laid and incubation was more likely to start after all females completed egg laying (which causes more synchronous egg hatching). Surprisingly, as a consequence, there were more surviving offspring in unfavourable conditions because the cooperative strategies resulted in fewer dead nestlings. To our knowledge, this study is the first theoretical analysis and empirical study demonstrating that an unfavourable environment reduces social conflict and results in better fitness consequences in social vertebrates.
Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan. shensf@gate.sinica.edu.tw
Sheng-Feng
SF
Shen
Sandra L
SL
Vehrencamp
Rufus A
RA
Johnstone
Hsiang-Ching
HC
Chen
Shih-Fan
SF
Chan
Wen-Yi
WY
Liao
Kai-Yin
KY
Lin
Hsiao-Wei
HW
Yuan
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D005260:Female; D008297:Male; D009425:Nesting Behavior / Q000502:physiology; D046109:Passeriformes / Q000502:physiology*; D013624:Taiwan