Data from: Parallel genetic adaptation across environments differing in mode of growth or resource availability

Evolution experiments have demonstrated high levels of genetic parallelism between populations evolving in identical environments. However, natural populations evolve in complex environments that can vary in many ways, likely sharing some characteristics but not others. Here we ask whether shared selection pressures drive parallel evolution across distinct environments. We addressed this question in experimentally evolved populations founded from a clone of the bacterium <i>Burkholderia cenocepacia</i>. These populations evolved for 90 days (approximately 600 generations) under all combinations of high or low carbon availability and selection for either planktonic or biofilm modes of growth. Populations that evolved in environments with shared selection pressures (either level of carbon availability or mode of growth) were more genetically similar to each other than populations from environments that shared neither characteristic. However, not all shared selection pressures led to parallel evolution. Genetic parallelism between low-carbon biofilm and low-carbon planktonic populations was very low despite shared selection for growth under low-carbon conditions, suggesting that evolution in low-carbon environments may generate stronger tradeoffs between biofilm and planktonic modes of growth. For all environments, a population’s fitness in a particular environment was positively correlated with the genetic similarity between that population and the populations that evolved in that particular environment. Although genetic similarity was low between low-carbon environments, overall, evolution in similar environments led to higher levels of genetic parallelism and that genetic parallelism, in turn, was correlated with fitness in a particular environment.

进化实验已证实，在相同环境中演化的种群之间存在高度的遗传平行性。然而，自然种群所处的环境复杂多变，往往仅共享部分特征而非全部。本研究旨在探讨共享的选择压力是否会在不同环境中推动平行进化。
本研究以从鼻疽伯克霍尔德菌（Burkholderia cenocepacia）单克隆菌株构建的实验演化种群为研究对象，这些种群在高/低碳可用性与浮游（planktonic）、生物膜（biofilm）生长模式选择的所有组合条件下演化了90天（约600代）。相较于未共享任何特征的环境来源种群，共享选择压力（即碳可用性水平或生长模式一致）的演化种群之间遗传相似性更高。但并非所有共享的选择压力均能引发平行进化：尽管低碳条件下的选择压力一致，但低碳生物膜种群与低碳浮游种群间的遗传平行性极低，这表明低碳环境中的演化可能在生物膜与浮游生长模式之间产生更强的权衡。
在所有环境中，种群在特定环境下的适合度与其和该环境下演化的其他种群之间的遗传相似性呈正相关。尽管低碳环境间的遗传相似性较低，但总体而言，在相似环境中演化的种群具有更高水平的遗传平行性，而遗传平行性又与种群在特定环境中的适合度相关。