Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan.
Department of Zoology, University of Oxford, Oxford OX1 3SZ, UK.
Proc Biol Sci. 2021 Sep 8;288(1958):20211491. doi: 10.1098/rspb.2021.1491.
Assessing the impact of environmental fluctuations on species coexistence is critical for understanding biodiversity loss and the ecological impacts of climate change. Yet determining how properties like the intensity, frequency or duration of environmental fluctuations influence species coexistence remains challenging, presumably because previous studies have focused on indefinite coexistence. Here, we model the impact of environmental fluctuations at different temporal scales on species coexistence over a finite time period by employing the concepts of time-windowed averaging and performance curves to incorporate temporal niche differences within a stochastic Lotka-Volterra model. We discover that short- and long-term environmental variability has contrasting effects on transient species coexistence, such that short-term variation favours species coexistence, whereas long-term variation promotes competitive exclusion. This dichotomy occurs because small samples (e.g. environmental changes over long time periods) are more likely to show large deviations from the expected mean and are more difficult to predict than large samples (e.g. environmental changes over short time periods), as described in the central limit theorem. Consequently, we show that the complex set of relationships among environmental fluctuations and species coexistence found in previous studies can all be synthesized within a general framework by explicitly considering both long- and short-term environmental variation.
评估环境波动对物种共存的影响对于理解生物多样性丧失和气候变化的生态影响至关重要。然而，确定环境波动的强度、频率或持续时间等属性如何影响物种共存仍然具有挑战性，这可能是因为之前的研究集中在无限期的共存上。在这里，我们通过使用时间窗口平均和性能曲线的概念，在随机Lotka-Volterra 模型中纳入时间生态位差异，来模拟不同时间尺度的环境波动对有限时间内物种共存的影响。我们发现，短期和长期环境变异性对暂态物种共存有相反的影响，即短期变化有利于物种共存，而长期变化则促进竞争排斥。这种二分法的出现是因为小样本（例如，长时间内的环境变化）比大样本（例如，短时间内的环境变化）更有可能出现与预期平均值的较大偏差，并且更难以预测，正如中心极限定理所描述的那样。因此，我们表明，通过明确考虑长期和短期环境变化，可以在一个通用框架内综合以前研究中发现的环境波动与物种共存之间复杂的关系。
