Male song stability shows cross-year repeatability but does not affect reproductive success in a wild passerine bird

Predictable behaviour (or “behavioural stability”) might be favoured in certain ecological contexts, e.g. when representing a quality signal. Costs associated with producing stable phenotypes imply selection should favour plasticity in stability when beneficial. Repeatable among-individual differences in degree of stability are simultaneously expected if individuals differ in ability to pay these costs, or in how they resolve cost-benefit trade-offs. Bird song represents a prime example, where stability may be costly yet beneficial when stable singing is a quality signal favoured by sexual selection. Assuming energetic costs, ecological variation (e.g. in food availability) should result in both within- and among-individual variation in stability. If song stability represents a quality signal, we expect directional selection favouring stable singers. For a three-year period, we monitored 12 nest box plots of great tits Parus major during breeding. We recorded male songs during simulated...可预测行为（或称“行为稳定性”）在特定生态情境下可能受到演化青睐，例如当其作为质量信号时。维持稳定表型所需的相关成本表明，当收益大于成本时，自然选择应倾向于稳定性的可塑性。若个体间在支付此类成本的能力，或是权衡成本与收益的策略上存在差异，则理论上也应存在个体间稳定性程度的可重复差异。鸟类鸣唱便是典型范例：稳定鸣唱可能需付出相应成本，但当稳定鸣唱作为性选择青睐的质量信号时，其收益显著。假设存在能量成本，那么生态变异（如食物可获得性变化）将导致稳定性同时出现个体内与个体间的变异。若鸣唱稳定性可作为质量信号，我们预期会出现青睐稳定鸣唱个体的定向选择。本研究在三年周期内，对12个大山雀（*Parus major*）巢箱样地的繁殖季进行了监测，并在模拟情境下记录雄性鸣唱……