LONG-TERM EXPERIMENTAL EVOLUTION IN ESCHERICHIA-COLI .1. ADAPTATION AND DIVERGENCE DURING 2,000 GENERATIONS
LONG-TERM EXPERIMENTAL EVOLUTION IN ESCHERICHIA-COLI .1. ADAPTATION AND DIVERGENCE DURING 2,000 GENERATIONS
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DOI：
10.1086/285289
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发表时间：
1991-12-01
影响因子：
2.9
通讯作者：
TADLER, SC
中科院分区：
文献类型：
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作者：
LENSKI, RE;ROSE, MR;TADLER, SC
我们评估了在独立进化的无性种群中，对统一环境的适应程度与这些种群分化的增加有关。此外，我们还关注适应模式本身，特别是在恒定环境中，平均适应度的增长率是否会随着选择的世代数而下降。平均适应度增长率与种群内适应度遗传方差之间的对应关系，正如费雪基本定理所期望的那样，也得到了解决。12个大肠杆菌群体是由一个单一的克隆祖先建立的，并允许进化2000代。平均健康水平提高了约37%。然而，在后代中，平均适应度的增长速度较慢。种群内遗传方差无统计学意义，种群间遗传方差有统计学意义。尽管种群内适应度的估计遗传变异在统计上并不显著，但在量级上与理论预期一致。同样，种群间的平均适应度方差与一个模型相一致，该模型包含了有限数量的非上位性位点上替换时间和顺序的随机变化，以及由克隆引起的替换延迟和替换之间的干扰。这些结果，作为一个整体，与理论预期是一致的，即在赖特的进化景观中，不会由于多个适合度峰值而引起分歧。
We assess the degree to which adaptation to a uniform environment among independently evolving asexual populations is associated with increasing divergence of those populations. In addition, we are concerned with the pattern of adaptation itself, particularly whether the rate of increase in mean fitness tends to decline with the number of generations of selection in a constant environment. The correspondence between the rate of increase in mean fitness and the within-population genetic variance of fitness, as expected from Fisher's fundamental theorem, is also addressed. Twelve Escherichia coli populations were founded from a single clonal ancestor and allowed to evolve for 2,000 generations. Mean fitness increased by about 37%. However, the rate of increase in mean fitness was slower in later generations. There was no statistically significant within-population genetic variance of fitness, but there was significant between-population variance. Although the estimated genetic variation in fitness within populations was not statistically significant, it was consistent in magnitude with theoretical expectations. Similarly, the variance of mean fitness between populations was consistent with a model that incorporated stochastic variation in the timing and order of substitutions at a finite number of nonepistatic loci, coupled with substitutions delays and interference between substitutions arising from clonality. These results, taken as a whole, are consistent with theoretical expectations that do not invoke divergence due to multiple fitness peaks in a Wrightian evolutionary landscape.