Department of Ecology and Biogeography, Nicolaus Copernicus University, Toruń, Poland.
Directorate D, Sustainable Resources, European Commission, Joint Research Centre, Ispra, Italy.
Ecology. 2019 Apr;100(4):e02623. doi: 10.1002/ecy.2623. Epub 2019 Mar 11.
Recent studies have highlighted the importance of higher-order competitive interactions in stabilizing population dynamics in multi-species communities. But how does the structure of competitive hierarchies affect population dynamics and extinction processes? We tackled this important question by using spatially explicit simulations of ecological drift (10 species in a homogeneous landscape of 64 patches) in which birth rates were influenced by interspecific competition. Specifically, we examined how transitive (linear pecking orders) and intransitive (pecking orders with loops) competitive hierarchies affected extinction rates and population dynamics in simulated communities through time. In comparison to a pure neutral model, an ecological drift model including transitive competition increased extinction rates, caused synchronous density-dependent population fluctuations, and generated a white-noise distribution of population sizes. In contrast, the drift model with intransitive competitive interactions decreased extinctions rates, caused asynchronous (compensatory) density-dependent population fluctuations, and generated a brown noise distribution of population sizes. We also explored the effect on community stability of more complex patterns of competitive interactions in which pairwise competitive relationships were assigned probabilistically. These probabilistic competition models also generated density-dependent trajectories and a brown noise distribution of population sizes. However, extinction rates and the degree of population synchrony were comparable to those observed in purely neutral communities. Collectively, our results confirm that intransitive competition has a strong and stabilizing effect on local populations in species-poor communities. This effect wanes with increasing species richness. Empirical assemblages characterized by brown spectral noise, density-dependent regulation, and asynchronous (compensatory) population fluctuations may indicate a signature of intransitive competitive interactions.
最近的研究强调了在多物种群落中，高阶竞争相互作用对稳定种群动态的重要性。但是，竞争等级结构如何影响种群动态和灭绝过程呢？我们通过使用空间显式模拟生态漂移（同质景观中有 64 个斑块的 10 个物种）来解决这个重要问题，其中出生率受到种间竞争的影响。具体来说，我们研究了传递（线性啄食顺序）和非传递（具有循环的啄食顺序）竞争等级结构如何通过时间影响模拟群落中的灭绝率和种群动态。与纯中性模型相比，包含传递竞争的生态漂移模型增加了灭绝率，导致同步密度依赖的种群波动，并产生了种群大小的白噪声分布。相比之下，具有非传递竞争相互作用的漂移模型降低了灭绝率，导致异步（补偿）密度依赖的种群波动，并产生了种群大小的棕噪声分布。我们还探索了更复杂的竞争相互作用模式对群落稳定性的影响，其中成对的竞争关系是概率分配的。这些概率竞争模型也产生了密度依赖的轨迹和种群大小的棕噪声分布。然而，灭绝率和种群同步程度与纯中性群落中观察到的相当。总的来说，我们的结果证实，在物种贫乏的群落中，非传递竞争对本地种群具有强大的稳定作用。这种作用随着物种丰富度的增加而减弱。具有棕谱噪声、密度依赖调节和异步（补偿）种群波动的经验组合可能表明存在非传递竞争相互作用的特征。
