Data from: Long-term dynamics of adaptation in asexual populations

Experimental studies of evolution have increased greatly in recent years, stimulated by the growing power of genomic tools. However, organismal fitness remains the ultimate metric for interpreting these experiments, and the dynamics of fitness remain poorly understood over long timescales. Here, we examine fitness trajectories for 12 Escherichia coli populations during 50,000 generations. Mean fitness appears to increase without bound, consistent with a power law. We also derive this power-law relation theoretically by incorporating clonal interference and diminishing-returns epistasis into a dynamical model of changes in mean fitness over time.近年来，受基因组学工具性能持续提升的推动，进化实验研究的规模大幅增长。然而，个体适合度（organismal fitness）仍是解读这类实验的核心衡量指标，且在长期时间尺度下，适合度的动态变化机制仍未得到充分解析。本研究针对12个大肠杆菌（Escherichia coli）种群在50000代演化过程中的适合度轨迹展开分析。研究结果显示，平均适合度呈现无上限增长的趋势，与幂律（power law）分布规律一致。本研究同时将克隆干扰与收益递减上位性纳入平均适合度随时间变化的动力学模型，从理论层面推导出了该幂律关系。