Experimental evolution of Pseudomonas fluorescens in simple and complex environments
Experimental evolution of Pseudomonas fluorescens in simple and complex environments
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DOI：
10.1086/444440
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发表时间：
2005-10-01
影响因子：
2.9
通讯作者：
Bell, G
中科院分区：
文献类型：
--
作者：
Barrett, RDH;MacLean, RC;Bell, G
在包含多种可替代资源的复杂环境中，谱系可能变得专门化，只消耗其中的一种或几种资源。在这里，我们研究了在化学定义的实验系统中，环境复杂性在确定近900代生态位宽度进化中的重要性。我们在不同复杂程度的环境中，通过在每个环境中使用1到8个碳底物，繁殖了120个荧光假单胞菌的复制系。在复杂环境中选择的群体的基因型比在简单环境中选择的群体的基因型进化出更大的适应度均值和方差。因此，谱系能够同时适应几种底物，而与培养基中存在的其他底物相比，没有任何明显的功能损失。在复杂环境中选择的种群中，适合度存在较大的遗传和基因型-环境相互作用方差。在复杂培养基上生长的群体中，遗传变异很可能是由于最适基因型的特性在不同的碳基质中存在差异。我们的研究结果表明，复杂环境中的进化既不会产生狭隘的专才，也不会产生完全的通才，而是产生重叠的不完善的通才，每个通才都适应了一定范围的底物，但不是全部。
In complex environments that contain several substitutable resources, lineages may become specialized to consume only one or a few of them. Here we investigate the importance of environmental complexity in determining the evolution of niche width over similar to 900 generations in a chemically defined experimental system. We propagated 120 replicate lines of the bacterium Pseudomonas fluorescens in environments of different complexity by using between one and eight carbon substrates in each environment. Genotypes from populations selected in complex environments evolved greater mean and variance in fitness than those from populations selected in simple environments. Thus, lineages were able to adapt to several substrates simultaneously without any appreciable loss of function with respect to other substrates present in the media. There was greater genetic and genotype-by-environment interaction variance for fitness within populations selected in complex environments. It is likely that genetic variance in populations grown on complex media was maintained because the identity of the fittest genotype varied among carbon substrates. Our results suggest that evolution in complex environments will result neither in narrow specialists nor in complete generalists but instead in overlapping imperfect generalists, each of which has become adapted to a certain range of substrates but not to all.