Data from: Transient synchrony among populations of five foliage-feeding Lepidoptera

1. Studies of transient population dynamics have largely focused on temporal changes in dynamical behavior, such as the transition between periods of stability and instability. The present study explores a related dynamic pattern, namely transient synchrony during a 49-year period among populations of five sympatric species of forest insects that share host tree resources. The long time-series allows a more comprehensive exploration of transient synchrony patterns than most previous studies. Considerable variation existed in the dynamics of individual species, ranging from periodic to aperiodic. 2. We used time-averaged methods to investigate long-term patterns of synchrony and time-localized methods to detect transient synchrony. We investigated transient patterns of synchrony between species and related these to the species’ varying density dependence structures; even species with very different density dependence exhibited at least temporary periods of synchrony. Observed periods of interspecific synchrony may arise from interactions with host trees (e.g. induced host defenses), interactions with shared natural enemies, or shared impacts of environmental stochasticity. 3. The transient nature of synchrony observed here raises questions both about the identity of synchronizing mechanisms and how these mechanisms interact with the endogenous dynamics of each species. We conclude that these patterns are the result of interspecific interactions that act only temporarily to synchronize populations, after which differences in the endogenous population dynamics among the species acts to desynchronize their dynamics.1. 瞬时种群动态（transient population dynamics）领域的现有研究多聚焦于种群动态行为的时间尺度变化，例如稳定阶段与不稳定阶段之间的状态转换。本研究探讨了一类相关动态模式——即共享寄主树木资源的5种同域森林昆虫种群在49年观测周期内呈现的瞬时同步性（transient synchrony）。相较于多数既往研究，本研究依托的长时间序列数据能够更全面地解析瞬时同步性的多样模式。各物种种群动态存在显著异质性，动态特征涵盖周期性至非周期性区间。 2. 本研究采用时间平均法（time-averaged methods）探究长期同步性模式，并借助时间局域化方法（time-localized methods）检测瞬时同步性。我们分析了物种种群间的瞬时同步模式，并将其与各物种差异化的密度依赖（density dependence）结构相关联；即便密度依赖特征差异显著的物种，也至少存在一段临时的同步阶段。观测到的种间同步性（interspecific synchrony）阶段，其成因可能包括与寄主树木的相互作用（例如诱导型寄主防御）、与共享天敌的相互作用，或是环境随机性（environmental stochasticity）带来的共同影响。 3. 本次研究观测到的同步性具有瞬时性特征，这一现象引发了两个核心议题：一是同步驱动机制的本质属性，二是这些机制如何与各物种种群的内源性动态（endogenous dynamics）产生相互作用。本研究最终得出结论：上述同步模式是种间相互作用的产物——这类相互作用仅在短期内实现种群同步，随后各物种种群内源性动态的差异会重新消解彼此的动态同步性。