Fate of a mutation in a fluctuating environment
Fate of a mutation in a fluctuating environment
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DOI：
10.1073/pnas.1505406112
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发表时间：
2015-09-08
影响因子：
11.1
通讯作者：
Desai, Michael M.
中科院分区：
文献类型：
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作者：
Cvijovic, Ivana;Good, Benjamin H.;Desai, Michael M.
自然环境从来不是真正不变的，但时间变化的选择压力的进化含义仍然知之甚少。在这里，我们研究了在波动的环境中，新突变的命运如何取决于环境变化的动态以及在每种条件下的选择压力。我们发现，即使一个突变在修复或灭绝之前经历了许多环境时期，它的命运也不一定由它的时间平均选择效应决定。取而代之的是，环境的可变性降低了在广泛的参数体系中选择的效率，使得选择无法区分平均而言是实质上有益的和实质上有害的突变。时间波动也可以显著增加固定概率，通常使这些波动的细节比作用于每个新突变的平均选择压力更重要。例如，导致条件之间权衡但平均而言有害的突变比总是中性或有益的突变更有可能修复。这些效应可能会对可变环境中的分子进化模式产生重要影响，它们表明，群体往往很难保持专业特征，即使这些特征的丧失会导致时间平均适应度的下降。
Natural environments are never truly constant, but the evolutionary implications of temporally varying selection pressures remain poorly understood. Here we investigate how the fate of a new mutation in a fluctuating environment depends on the dynamics of environmental variation and on the selective pressures in each condition. We find that even when a mutation experiences many environmental epochs before fixing or going extinct, its fate is not necessarily determined by its time-averaged selective effect. Instead, environmental variability reduces the efficiency of selection across a broad parameter regime, rendering selection unable to distinguish between mutations that are substantially beneficial and substantially deleterious on average. Temporal fluctuations can also dramatically increase fixation probabilities, often making the details of these fluctuations more important than the average selection pressures acting on each new mutation. For example, mutations that result in a trade-off between conditions but are strongly deleterious on average can nevertheless be more likely to fix than mutations that are always neutral or beneficial. These effects can have important implications for patterns of molecular evolution in variable environments, and they suggest that it may often be difficult for populations to maintain specialist traits, even when their loss leads to a decline in time-averaged fitness.