Temporal scale of environmental correlations affects ecological synchrony

Population densities of a species, measured in different locations are often correlated over time, a phenomenon referred to as synchrony. Synchrony results from dispersal of individuals among locations and spatially correlated environmental variation, among other causes. Synchrony is often measured by a correlation coefficient. However, synchrony can vary with timescale. We demonstrate theoretically and experimentally that the timescale-specificity of environmental correlation affects the overall magnitude and timescale-specificity of synchrony, and that these effects are modified by population dispersal. Our laboratory experiments linked populations of flour beetles by changes in habitat size and dispersal. Linear filter theory, applied to a metapopulation model for the experimental system, predicted the observed timescale-specific effects. The timescales at which environmental covariation occurs can affect the population dynamics of species in fragmented habitats.

不同观测地点的某一物种种群密度随时间往往存在相关性，这一现象被称为同步性（synchrony）。同步性的成因包括种群个体在不同地点间的扩散、空间相关的环境变异等多种因素。同步性通常通过相关系数进行量化。但同步性会随时间尺度发生变化。本研究通过理论推导与实验验证证实：环境相关性的时间尺度特异性会影响同步性的整体强度与时间尺度特异性，且种群扩散会对上述效应产生调控作用。本研究的实验室实验通过改变生境规模与扩散强度，构建了互相关联的面粉甲虫种群体系。应用于本实验系统的集合种群（metapopulation）模型的线性滤波理论，准确预测了实验中观测到的时间尺度特异性效应。环境协变发生的时间尺度，会对破碎化生境中物种的种群动态产生影响。