Data from: The scaling of population persistence with carrying capacity does not asymptote in populations of a fish experiencing extreme climate variability

Despite growing concerns regarding increasing frequency of extreme climate events and declining population sizes, the influence of environmental stochasticity on the relationship between population carrying capacity and time-to-extinction has received little empirical attention. While time-to-extinction increases exponentially with carrying capacity in constant environments, theoretical models suggest increasing environmental stochasticity causes asymptotic scaling, thus making minimum viable carrying capacity vastly uncertain in variable environments. Using empirical estimates of environmental stochasticity in fish metapopulations, we showed that increasing environmental stochasticity resulting from extreme droughts was insufficient to create asymptotic scaling of time-to-extinction with carrying capacity in local populations as predicted by theory. Local time-to-extinction increased with carrying capacity due to declining sensitivity to demographic stochasticity, and the slope of this relationship declined significantly as environmental stochasticity increased. However, recent 1-in-25 yr extreme droughts were insufficient to extirpate populations with large carrying capacity. Consequently, large populations may be more resilient to environmental stochasticity than previously thought. The lack of carrying capacity-related asymptotes in persistence under extreme climate variability reveals how small populations affected by habitat loss or overharvesting, may be disproportionately threatened by increases in extreme climate events with global warming.尽管人们日益担忧极端气候事件发生频率攀升与种群数量下降的现状，但环境随机性（environmental stochasticity）对种群承载力（carrying capacity）与灭绝时间（time-to-extinction）之间关系的影响，却鲜有实证研究予以关注。在恒定环境中，灭绝时间随种群承载力呈指数增长；但理论模型表明，不断增强的环境随机性会催生渐近标度关系，进而使得可变环境中的最小可行承载力存在极大不确定性。本研究借助鱼类集合种群（fish metapopulations）的环境随机性实证估计值，证实极端干旱引发的环境随机性增强，并未如理论预测那般，使局域种群的灭绝时间随承载力呈现渐近标度关系。局域种群的灭绝时间随承载力提升而延长，这源于其对种群统计随机性（demographic stochasticity）的敏感性下降，且该关系的斜率会随环境随机性增强而显著降低。不过，近期发生的25年一遇极端干旱，并未导致承载力较高的种群走向灭绝。由此可见，大型种群对环境随机性的抗逆能力可能远超此前预期。极端气候变异下，种群存续时长并未出现与承载力相关的渐近标度，这一发现揭示了：受栖息地丧失或过度捕捞影响的小型种群，可能会因全球变暖引发的极端气候事件增多，而面临不成比例的生存威胁。