Current spring warming as a driver of selection on reproductive timing in a wild passerine

1. Evolutionary adaptation as a response to climate change is expected for fitness-related traits affected by climate and exhibiting genetic variance. Although the relationship between warmer spring temperature and earlier timing of reproduction is well documented, quantifications and predictions of the impact of global warming on natural selection acting on phenology in wild populations remain rare. If global warming affects fitness in a similar way across individuals within a population, or if fitness consequences are independent of phenotypic variation in key-adaptive traits, then no evolutionary response is expected for these traits. 2. Here we quantified the selection pressures acting on laying date during a 24-year monitoring of blue tits in southern Mediterranean France, a hot spot of climate warming. We explored the temporal fluctuation in annual selection gradients and we determined its temperature-related drivers. 3. We first investigated the month-specific warming since 1970 ...1. 针对受气候影响且存在遗传变异的适合度（fitness）相关性状，其作为气候变化响应的进化适应是可预期的。尽管春季气温升高与繁殖物候提前的关联已得到充分证实，但针对全球变暖对野生种群物候（phenology）所受自然选择的影响进行量化与预测的研究仍较为匮乏。若全球变暖对种群内个体适合度的影响模式一致，或其适合度效应与关键适应性性状的表型变异无关，则这些性状不会产生进化响应。 2. 本研究通过对法国地中海南部这一全球气候变暖热点区域的蓝山雀（blue tits）开展长达24年的监测，量化了产卵日期（laying date）所受的选择压力；我们探究了年度选择梯度（selection gradients）的时间波动特征，并明确了其温度相关的驱动因素。 3. 我们首先分析了1970年以来各月的气候变暖情况……