Data from: Evolutionary responses to crude oil from the Deepwater Horizon oil spill by the copepod Eurytemora affinis

The BP Deepwater Horizon Oil Disaster was the most catastrophic offshore oil spill in U.S. history, yet we still have a poor understanding of how organisms could evolve in response to the toxic effects of crude oil. This study offers a rare analysis of how fitness-related traits could evolve rapidly in response to crude oil toxicity. We examined evolutionary responses of populations of the common copepod Eurytemora affinis residing in the Gulf of Mexico, by comparing crude oil tolerance of populations collected before versus after the Deepwater Horizon oil spill of 2010. In addition, we imposed laboratory selection for crude oil tolerance for ~8 generations, using an E. affinis population collected from before the oil spill. We found evolutionary increases in crude oil tolerance in the wild population following the oil spill, relative to the population collected before the oil spill. The post-oil spill population showed increased survival and rapid development time in the presence of crude oil. In contrast, evolutionary responses following laboratory selection were less clear; though, development time from metamorphosis to adult in the presence of crude oil did become more rapid after selection. We did find that the wild population, used in both experiments, harbored significant genetic variation in crude oil tolerance, upon which selection could act. Thus, our study indicated that crude oil tolerance could evolve, but perhaps not on the relatively short time scale of the laboratory selection experiment. This study contributes novel insights into evolutionary responses to crude oil, in directly examining fitness-related traits before and after an oil spill, and in observing evolutionary responses following laboratory selection.

英国石油公司（BP）深水地平线石油灾难是美国历史上最具灾难性的近海原油泄漏事件，但目前学界对生物如何响应原油毒性产生适应性演化仍知之甚少。本研究针对生物如何快速演化出与适合度（fitness）相关的性状以应对原油毒性，开展了罕见的分析。我们以栖息于墨西哥湾的常见桡足类（copepod）近缘真哲水蚤（Eurytemora affinis）种群为研究对象，通过对比2010年深水地平线原油泄漏事件发生前后采集的种群的原油耐受性，探究其演化响应。此外，我们利用泄漏事件前采集的近缘真哲水蚤种群，在实验室中开展了约8代的原油耐受性人工选择实验。我们发现，相较于泄漏事件前采集的种群，泄漏事件后的野生种群原油耐受性出现了演化提升：在原油暴露环境下，该种群的存活率更高、发育时长更短。与之相对，实验室选择实验后的演化响应则不甚明确；不过，在原油暴露条件下，从变态发育至成虫的时长在选择后确实有所缩短。我们确实发现，两项实验共用的野生种群在原油耐受性上存在显著的遗传变异，这为选择作用提供了作用基础。因此，本研究表明原油耐受性可以发生演化，但或许无法在实验室选择实验相对较短的时间尺度内完成。本研究通过直接对比原油泄漏事件前后的适合度相关性状，并观测实验室选择实验下的演化响应，为原油毒性相关的演化研究提供了全新的认知。