Metapopulation stability in branching river networks
Metapopulation stability in branching river networks
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DOI：
10.1073/pnas.1800060115
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发表时间：
2018-06
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影响因子：
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通讯作者：
Akira Terui;Nobuo Ishiyama;Hirokazu Urabe;S. Ono;J. Finlay;F. Nakamura
中科院分区：
文献类型：
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作者：
Akira Terui;Nobuo Ishiyama;Hirokazu Urabe;S. Ono;J. Finlay;F. Nakamura
集合种群稳定性是一个重要的生态特性。虽然生态系统的大小被认为是集合种群稳定性的基本驱动力，目前的理论在简化的景观可能不适合复杂的分支生态系统，如河流。在这里，我们表明，分形河流网络，分支的复杂性（分支概率测量）的尺度独立的特性，稳定流域集合种群。我们从理论上揭示了分支复杂性和集合种群稳定性之间的强关联是纯粹概率过程的结果。此外，稳定效果的分支复杂性一致观察到的集合种群的四个生态不同的河流鱼类。因此，分支复杂性可能是分支生态系统中集合种群稳定性的普遍存在的因素。这种复杂性的丧失可能会破坏集合种群的恢复力。种内种群多样性（特别是种群动态的空间多样性）是自然界集合种群稳定性和持久性的重要组成部分。在二维系统中，理论预测集合种群的稳定性应该随着生态系统的规模（或栖息地网络的规模）而增加：较大的生态系统将拥有更多样化的亚种群，具有更稳定的聚集动态。然而，目前的理论在简化的景观可能不足以预测分支生态系统，一个被忽视的，但广泛的栖息地几何的紧急性能。在这里，我们结合联合收割机理论和一个独特的长期数据集的分析表明，分形河流网络的尺度不变的特点，分支的复杂性（测量分支概率），稳定流域集合种群。在河流系统中，每个分支（即，支流）表现出独特的生态动态，汇合处作为这些分支的“合并”点。因此，分支复杂性水平的增加应该赋予在景观上整合异步动态的更大可能性。我们从理论上揭示了分支复杂性的稳定作用是自然条件下纯概率过程的结果，其中分支内同步超过分支间同步。与目前在二维系统中发展的理论相反，集合种群的大小（与生态系统大小密切相关的变量）对集合种群的稳定性有模糊的影响。这些理论预测支持18年的观察鱼类种群在31个流域：我们的跨流域的比较显示一致的稳定效果的分支复杂性非常不同的河流鱼类的集合种群。分支复杂性和集合种群稳定性之间的强关联可能是分支网络的一个普遍特征，在快速的环境变化过程中强烈影响物种的持久性。
Significance Metapopulation stability is a critical ecological property. Although ecosystem size has been considered as a fundamental driver of metapopulation stability, current theories developed in simplified landscapes may not be appropriate for complex branching ecosystems, such as rivers. Here, we show that a scale-independent characteristic of fractal river networks, branching complexity (measured as branching probability), stabilizes watershed metapopulations. We theoretically revealed that a strong association between branching complexity and metapopulation stability is a consequence of purely probabilistic processes. Furthermore, the stabilizing effect of branching complexity was consistently observed in metapopulations of four ecologically distinct riverine fishes. Hence, branching complexity may be a ubiquitous agent of metapopulation stability in branching ecosystems. The loss of such complexity may undermine resilience of metapopulations. Intraspecific population diversity (specifically, spatial asynchrony of population dynamics) is an essential component of metapopulation stability and persistence in nature. In 2D systems, theory predicts that metapopulation stability should increase with ecosystem size (or habitat network size): Larger ecosystems will harbor more diverse subpopulations with more stable aggregate dynamics. However, current theories developed in simplified landscapes may be inadequate to predict emergent properties of branching ecosystems, an overlooked but widespread habitat geometry. Here, we combine theory and analyses of a unique long-term dataset to show that a scale-invariant characteristic of fractal river networks, branching complexity (measured as branching probability), stabilizes watershed metapopulations. In riverine systems, each branch (i.e., tributary) exhibits distinctive ecological dynamics, and confluences serve as “merging” points of those branches. Hence, increased levels of branching complexity should confer a greater likelihood of integrating asynchronous dynamics over the landscape. We theoretically revealed that the stabilizing effect of branching complexity is a consequence of purely probabilistic processes in natural conditions, where within-branch synchrony exceeds among-branch synchrony. Contrary to current theories developed in 2D systems, metapopulation size (a variable closely related to ecosystem size) had vague effects on metapopulation stability. These theoretical predictions were supported by 18-y observations of fish populations across 31 watersheds: Our cross-watershed comparisons revealed consistent stabilizing effects of branching complexity on metapopulations of very different riverine fishes. A strong association between branching complexity and metapopulation stability is likely to be a pervasive feature of branching networks that strongly affects species persistence during rapid environmental changes.