Measures of the seasonal timing of biological events are key to addressing questions about how phenology evolves, modifies species interactions, and mediates biological responses to climate change. Phenology is often characterized in terms of discrete events, such as a date of first flowering or arrival of first migrants. We discuss how phenological events that are typically measured at the population or species level arise from distributions of phenological events across seasons, and from norms of reaction of these phenological events across environments. We argue that individual variation in phenological distributions and reaction norms has important implications for how we should collect, analyze, and interpret phenological information. Regarding phenology as a reaction norm rather than one year's specific values implies that selection acts on the phenologies that an individual expresses over its lifetime. To understand how climate change is likely to influence phenology, we need to consider not only plastic responses along the reaction norm but changes in the reaction norm itself. We show that when individuals vary in their reaction norms, correlations between reaction norm elevation and slope make first events particularly poor estimators of population sensitivity to climate change, and variation in slopes can obscure the pattern of selection on phenology. We also show that knowing the shape of the distribution of phenological events across the season is important for predicting biologically important phenological mismatches with climate change. Last, because phenological events are parts of a continuous developmental process, we suggest that the approach of measuring phenology by recording developmental stages of individuals in a population at a single point in time should be used more widely. We conclude that failure to account for phenological distributions and reaction norms may lead to overinterpretation of metrics based on single events, such as commonly recorded first event dates, and may confound meta‐analyses that use a range of metrics. Rather than prescribing a single universal approach to studying phenology, we point out limitations of inferences based on single metrics and encourage work that considers the multivariate nature of phenology and more tightly links data collection and analyses with biological hypotheses.

中文翻译：

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物候学是一个过程，而不是一个事件：从个人反应规范到社区指标

衡量生物事件的季节性时机是解决有关物候学如何演变，改变物种相互作用以及介导对气候变化的生物学响应的问题的关键。物候学通常以离散事件为特征，例如第一次开花的日期或第一次迁徙者的到来。我们讨论了通常在种群或物种水平上测量的物候事件是如何由各个季节的物候事件的分布以及跨环境的这些物候事件的反应规范引起的。我们认为，物候分布和反应规范的个体差异对我们应如何收集，分析和解释物候信息具有重要意义。将物候学作为一种反应规范而不是一年 s的特定值表示选择会影响个人在其一生中表达的物候。要了解气候变化可能如何影响物候学，我们不仅需要考虑沿反应规范的塑性响应，而且还要考虑反应规范本身的变化。我们表明，当个人的反应规范发生变化时，反应规范的升高与坡度之间的相关性会首先引起人们对气候变化敏感性的估计尤其差的第一事件，并且坡度的变化会掩盖物候选择的模式。我们还表明，了解整个季节的物候事件分布的形状对于预测与气候变化具有重要生物学意义的物候不匹配非常重要。最后，由于物候事件是持续发展过程的一部分，我们建议应更广泛地使用通过记录单个时间点上某个人群的发育阶段来衡量物候的方法。我们得出的结论是，无法解释物候分布和反应规范可能会导致基于单个事件（如通常记录的首次事件日期）的指标过度解释，并可能混淆使用一系列指标的荟萃分析。我们没有规定单一的通用方法来研究物候学，而是指出了基于单一指标的推理的局限性，并鼓励考虑物候学的多变量性质并更紧密地将数据收集和分析与生物学假设联系起来的工作。