An experimental test of the effects of dispersal and the paradox of enrichment on metapopulation persistence
An experimental test of the effects of dispersal and the paradox of enrichment on metapopulation persistence
复制标题
扩散和富集悖论对集合种群持久性影响的实验测试
作者：
E. Laan;J. Fox
许多物种表现出高振幅，灭绝倾向的周期，例如由于资源富集（称为富集悖论）。这些物种是如何生存下来的？一种可能性是集合种群动态，但尚不清楚这些是否可以缓解富集悖论。富集的悖论可能会增加当地人口灭绝率，也可能增加人口波动的空间同步性，因为人口周期很容易同步，即使是低速率的扩散。空间同步的种群波动将不会留下拯救效应的空间，空间同步的局部波动将不会留下非对称化的来源。我们进行了一个原生动物的微观宇宙实验，以测试如何分散和富集影响持久性的捕食者-猎物集合种群通过改变空间同步性。我们收集了54个，4-补丁集合种群的原生生物捕食者游仆虫patella和它的原生生物捕食四膜虫梨形。每个集合种群经历了九个扩散率之一，与六个富集水平之一。我们测试了富集和扩散对捕食者-被捕食者循环幅度、捕食者种群灭绝风险、捕食者种群波动的空间同步性和捕食者集合种群持续时间的影响。富集增加捕食者-猎物周期的振幅，但没有检测到的影响种群灭绝的风险。扩散对捕食者-被捕食者循环振幅没有影响。空间同步性增加丰富和分散。集合种群的持久性降低丰富和空间同步。我们的结论是，增加富集减少集合种群的持久性，主要是通过增加空间同步性的地方precision，而不是通过增加他们的频率。这些结果突出了同步预防机制对集合种群持久性的重要性。
Many species exhibit high‐amplitude, extinction‐prone cycles, for instance due to resource enrichment (called the paradox of enrichment). How do such species manage to persist? One possibility is metapopulation dynamics, but it is unclear if these can mitigate the paradox of enrichment. The paradox of enrichment might increase local population extinction rates, and might also increase the spatial synchrony of population fluctuations because population cycles are easily synchronized by even low rates of dispersal. Spatially‐synchronous population fluctuations would leave no scope for rescue effects, and spatially‐synchronous local extinctions would leave no source for recolonization. We conducted a protist microcosm experiment to test how dispersal and enrichment affect the persistence of predator–prey metapopulations by altering spatial synchrony. We assembled 54, 4‐patch metapopulations of the protist predatorEuplotes patellaand its protist preyTetrahymena pyriformis. Each metapopulation experienced one of nine dispersal rates, crossed with one of six enrichment levels. We tested the effects of enrichment and dispersal on predator–prey cycle amplitude, predator population extinction risk, spatial synchrony of predator population fluctuations, and predator metapopulation persistence time. Enrichment increased predator–prey cycle amplitude but had no detectable effect on population extinction risk. Dispersal had no effect on predator–prey cycle amplitude. Spatial synchrony increased with enrichment and dispersal. Metapopulation persistence decreased with enrichment and spatial synchrony. We conclude that increasing enrichment reduced metapopulation persistence primarily by increasing spatial synchrony of local extinctions, rather than by increasing their frequency. These results highlight the importance of synchrony‐preventing mechanisms for metapopulation persistence.