Data from: Harvested populations are more variable only in more variable environments

The interaction between environmental variation and population dynamics is of major importance, particularly for managed and economically important species, and especially given contemporary changes in climate variability. Recent analyses of exploited animal populations contested whether exploitation or environmental variation has the greatest influence on the stability of population dynamics, with consequences for variation in yield and extinction risk. Theoretical studies however have shown that harvesting can increase or decrease population variability depending on environmental variation, and requested controlled empirical studies to test predictions. Here, we use an invertebrate model species in experimental microcosms to explore the interaction between selective harvesting and environmental variation in food availability in affecting the variability of stage-structured animal populations over 20 generations. In a constant food environment, harvesting adults had negligible impact on population variability or population size, but in the variable food environments, harvesting adults increased population variability and reduced its size. The impact of harvesting on population variability differed between proportional and threshold harvesting, between randomly and periodically varying environments, and at different points of the time series. Our study suggests that predicting the responses to selective harvesting is sensitive to the demographic structures and processes that emerge in environments with different patterns of environmental variation.

环境变异（environmental variation）与种群动态（population dynamics）之间的相互作用具有核心重要性，尤其对于受管理及具有经济重要性的物种而言，在当前气候变异发生变化的背景下尤为如此。近期针对被开发利用的动物种群的研究，就开发活动与环境变异二者中何者对种群动态稳定性的影响更大这一问题引发了争议，该争议亦会对产量变异及灭绝风险产生影响。不过，理论研究表明，捕捞对种群变异性的影响可能因环境变异而异，既可提升也可降低种群变异性，同时呼吁开展控制性实证研究以验证相关预测。本研究利用实验微型生态系统（microcosm）中的无脊椎动物模式物种，探究选择性捕捞与食物可获得性的环境变异之间的相互作用，及其在20个世代内对分阶段结构动物种群变异性的影响。在食物环境恒定的条件下，捕捞成体对种群变异性或种群规模几乎无影响；但在食物环境存在变异的条件下，捕捞成体则会提升种群变异性并降低种群规模。捕捞对种群变异性的影响，在比例捕捞与阈值捕捞之间、随机变异与周期性变异环境之间，以及时间序列的不同节点均存在差异。本研究表明，对选择性捕捞响应的预测，会因不同环境变异模式下所形成的种群统计结构与过程而异。