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.尽管学界对极端气候事件发生频率上升、物种种群规模持续下降的担忧与日俱增，但环境随机性（environmental stochasticity）对种群环境容纳量（carrying capacity）与灭绝时间（time-to-extinction）之间关系的影响，却鲜有实证研究关注。尽管在恒定环境中，灭绝时间会随环境容纳量呈指数增长，但理论模型显示，环境随机性的增强会导致渐近标度关系，进而使得可变环境中的最小可存活环境容纳量（minimum viable carrying capacity）变得极不确定。本研究借助鱼类集合种群（fish metapopulations）中环境随机性的实证估算数据，证实极端干旱引发的环境随机性增强，并未如理论预测那样，导致局域种群的灭绝时间与环境容纳量之间出现渐近标度关系。由于对局域种群统计随机性（demographic stochasticity）的敏感性下降，局域种群的灭绝时间会随环境容纳量上升而增加，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，不足以导致环境容纳量较大的种群发生局域灭绝。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的认知。在极端气候变异性下，种群存续未出现与环境容纳量相关的渐近线，这一现象揭示了：受栖息地丧失或过度捕捞影响的小型种群，可能会因全球变暖背景下极端气候事件的增多，受到不成比例的威胁。