Extent of adaptation is not limited by unpredictability of the environment in laboratory populations of Escherichia coli

Environmental variability is on the rise in different parts of the earth and the survival of many species depend on how well they cope with these fluctuations. Our current understanding of how organisms adapt to unpredictably fluctuating environments is almost entirely based on studies that investigate fluctuations among different values of a single environmental stressor like temperature or pH. How would unpredictability affect adaptation when the environment fluctuates between qualitatively very different kinds of stresses? To answer this question, we subjected laboratory populations of Escherichia coli to selection over ~260 generations. The populations faced predictable and unpredictable environmental fluctuations across qualitatively different selection environments, namely, salt and acidic pH. We show that predictability of environmental fluctuations does not play a role in determining the extent of adaptation, although the extent of ancestral adaptation to the chosen selection e...

地球不同区域的环境变异性正日益加剧，诸多物种的生存取决于其应对此类环境波动的能力。目前学界对生物如何适应不可预测环境波动的认知，几乎全部源自针对单一环境胁迫因子（如温度或pH值）不同取值间波动的研究。当环境在性质迥异的两类胁迫之间波动时，不可预测性将如何影响生物的适应过程？为解答这一问题，我们对大肠杆菌（Escherichia coli）的实验室种群开展了约260代的选择实验。这些种群在盐胁迫与酸性pH环境这两种性质截然不同的选择环境间，经历了可预测与不可预测的环境波动。研究结果显示，环境波动的可预测性并未对适应程度产生显著影响，尽管受试种群对所选选择环境的祖先适应程度……