Drought effects on invertebrate metapopulation dynamics and quasi‐extinction risk in an intermittent river network
Drought effects on invertebrate metapopulation dynamics and quasi‐extinction risk in an intermittent river network
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DOI：
10.1111/gcb.15720
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发表时间：
2021-05
影响因子：
11.6
通讯作者：
Romain Sarremejane;R. Stubbington;J. England;C. Sefton;Michael Eastman;S. Parry;A. Ruhí
中科院分区：
文献类型：
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作者：
Romain Sarremejane;R. Stubbington;J. England;C. Sefton;Michael Eastman;S. Parry;A. Ruhí
如果生态群落的组成物种具有不同的抵抗力和复原力策略，那么它们在面对干扰时就能保持稳定。反过来，如果异质景观在离散种群之间保持空间异步，则局部稳定性会在区域范围内扩大，但如果大规模压力源同步环境条件和生物反应，则局部稳定性不会扩大。在这里，我们假设干旱可以通过过滤掉当地适应不良的物种以及同步它们在整个河流网络中的动态来极大地降低无脊椎动物集合种群的稳定性。我们通过多元自回归状态空间（MARSS）模型对空间复制的长期数据测试了这一假设，这些数据描述了一组温带低地溪流遭受季节性和超季节干燥事件的水生无脊椎动物群落和水文条件。这种定量方法使我们能够评估局部（流量大小）和网络规模（水文连通性）驱动因素对无脊椎动物长期轨迹的影响，并模拟对一系列干旱情景的近期反应。我们发现，不同群落的物种丰度波动是异质的，并且是由水文和随机驱动因素共同驱动的。在集合种群中，干旱范围的增加减少了具有低抵抗力或恢复能力（即分别在原地持续存在或从其他地方重新殖民的能力低）的功能群的丰度。我们的模拟显示，随着河网内流动生境的收缩，易受干旱影响的类群的集合种群准灭绝风险呈指数级增加，而具有抗性和恢复力特征的类群的风险保持稳定。我们的研究结果表明，干旱可能是河流景观的同步因素，可能导致抵抗力和恢复能力较低的物种出现区域性准灭绝。随着全球范围内极端水文气候的持续加剧，更好地认识干旱驱动的同步可能会增加物种灭绝预测的现实性。
Ecological communities can remain stable in the face of disturbance if their constituent species have different resistance and resilience strategies. In turn, local stability scales up regionally if heterogeneous landscapes maintain spatial asynchrony across discrete populations—but not if large‐scale stressors synchronize environmental conditions and biological responses. Here, we hypothesized that droughts could drastically decrease the stability of invertebrate metapopulations both by filtering out poorly adapted species locally, and by synchronizing their dynamics across a river network. We tested this hypothesis via multivariate autoregressive state‐space (MARSS) models on spatially replicated, long‐term data describing aquatic invertebrate communities and hydrological conditions in a set of temperate, lowland streams subject to seasonal and supraseasonal drying events. This quantitative approach allowed us to assess the influence of local (flow magnitude) and network‐scale (hydrological connectivity) drivers on invertebrate long‐term trajectories, and to simulate near‐future responses to a range of drought scenarios. We found that fluctuations in species abundances were heterogeneous across communities and driven by a combination of hydrological and stochastic drivers. Among metapopulations, increasing extent of dry reaches reduced the abundance of functional groups with low resistance or resilience capacities (i.e. low ability to persist in situ or recolonize from elsewhere, respectively). Our simulations revealed that metapopulation quasi‐extinction risk for taxa vulnerable to drought increased exponentially as flowing habitats contracted within the river network, whereas the risk for taxa with resistance and resilience traits remained stable. Our results suggest that drought can be a synchronizing agent in riverscapes, potentially leading to regional quasi‐extinction of species with lower resistance and resilience abilities. Better recognition of drought‐driven synchronization may increase realism in species extinction forecasts as hydroclimatic extremes continue to intensify worldwide.