Later onset of breeding in an apex predator in response to climate change: causes and consequences

气候变化对21世纪的野生动物种群和生物多样性构成最根本的威胁之一。长期的研究对于更深入地了解这种变化的原因和后果至关重要，特别是在顶端捕食者中。在普通秃鹫Buteo Buteo的种群中，尽管气温变暖，但在1990-2010年间，平均繁殖开始时间倒退了一周以上。我们建议探索哪种机制可能最好地解释这一矛盾的结果，并阐明生物对气候变化反应的复杂性。通过包括繁殖次数、繁殖成功、个体生活史和健康状况的数据，可以检验六个主要假设。后来的繁殖是由适应性进化反应、表型可塑性、气候的松弛选择压力、个体条件恶化或年龄结构或羽毛分布的变化来解释的吗？最有可能的机制是如何与生活史相互作用来影响种群动态？22年来汇编的500多部生活史将记录不同群体之间在应对气候变化方面的权衡变化。人口动态将用时间序列分析和以天气为协变量的矩阵模型来模拟，以找出影响人口增长和波动的关键因素。结果将推广到另一种顶端捕食者--苍鹰，自1975年以来一直在同一研究区域进行研究。使用两个物种和相同的区域，可以找到种群增长和波动的一般关联。结果将使用关于常见秃鹫种群动态的独特的大陆尺度元数据进一步推广，目前有115个持续时间至少为10年的时间序列。

Climate change poses one of the most fundamental risks to wildlife populations and biodiversity in the 21st century. Long-term studies are vital to obtain a deeper understanding of the causes and consequences of this change, especially in apex predators. In a population of common buzzards Buteo buteo, average onset of breeding has shifted backwards by over a week over the time period 1990-2010, despite warmer temperatures. We propose to explore which mechanism might best explain this paradoxical result and elucidate the complexity of organisms’ responses to climate change. With data covering breeding times, reproductive success, life histories of individuals and fitness, six major hypotheses can be tested. Is later breeding explained by an adaptive evolutionary response, phenotypic plasticity, relaxed selection pressure by climate, worsening of individual condition, or changes in the age structure or plumage distribution? How does the most likely mechanism interact with the life history to influence population dynamics? Over 500 life histories compiled across 22 years will document shifts in trade-offs between cohorts in response to climate change. Population dynamics will be modelled with time series analyses and matrix models with weather as a covariate to find key factors influencing population growth and fluctuations. Results will be generalized to another apex predator, the goshawk Accipiter gentilis which has been studied in the same study area since 1975. Using two species and the same area, allows general correlates of population growth and fluctuations to be found. Results will be further generalized using a unique continental scale metadata set on common buzzard population dynamics with currently 115 time series of at least 10 year duration.