Spatial variation buffers temporal fluctuations in early juvenile survival for an endangered Pacific salmon

1. Spatial, phenotypic, and genetic diversity at relatively small scales can buffer species against large-scale processes such as climate change that tend to synchronize populations and increase temporal variability in overall abundance or production. This portfolio effect generally results in improved biological and economic outcomes for managed species. Previous evidence for the portfolio effect in salmonids has arisen from examinations of time series of adult abundance, but we lack evidence of spatial buffering of temporal variability in demographic rates such as survival of juveniles during their first year of life. 2. We therefore use density-dependent population models with multiple random effects to represent synchronous (similar among populations) and asynchronous (different among populations) temporal variability as well as spatial variability in survival. These are fitted to 25 years of survey data for breeding adults and surviving juveniles from 15 demographically distinct po...

1. 较小尺度下的空间、表型与遗传多样性，可帮助物种抵御气候变化等大尺度过程——这类过程往往会同步种群动态，并提升总丰度或总产量的时间变异性。这种投资组合效应（portfolio effect）通常能提升受管理物种的生物学与经济学效益。此前关于鲑科鱼类（salmonids）投资组合效应的证据，均来自对成体丰度时间序列的分析，但我们尚未获得种群动态率（如幼体生命第一年的存活率）的时间变异性受空间缓冲作用的相关证据。2. 为此，我们采用包含多重随机效应的密度依赖种群模型（density-dependent population models），来表征种群间同步（即种群间特征相似）与异步（即种群间特征相异）的时间变异性，以及存活率的空间变异性。我们将该模型拟合自15个种群动态特征各异的种群的25年调查数据，这些数据涵盖繁殖成体与存活幼体的相关信息……