The distribution of fitness effects in an uncertain world.
The distribution of fitness effects in an uncertain world.
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DOI：
10.1111/evo.12673
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发表时间：
2015-06
期刊：
影响因子：
--
通讯作者：
Clark AG
中科院分区：
文献类型：
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作者：
Connallon T;Clark AG
新出现的突变中适应度效应（DFE）的分布对进化生物学和数量遗传学的广泛研究主题具有关键影响。虽然数学模型在预测和解释DFE的经验特征方面发挥了重要作用，但该理论在很大程度上忽略了环境异质性，以及与单一种群相关的环境背景之间的适应性遗传权衡的潜力。环境变化可以通过两种可能的途径随时间或空间改变适应性的遗传基础：（1）通过改变自然选择的方向;（2）通过改变给定基因型表达的表型（即，表型可塑性）。虽然这两种现象在自然界中被广泛观察到，但它们对DFE的影响尚未纳入正式模型。在这里，我们开发了一个扩展的Fisher几何模型，明确考虑波动的选择和可塑性的DFE的相对影响。我们发现，环境异质性通常加剧了进化的限制，减少了有益的突变的比例，并增加了环境背景之间的适应性权衡的普遍性。在这个意义上，环境异质性和多效性对适应有类似的影响。我们表明，异质性-如多效性-限制了适应性进化的遗传途径的范围，并增加了适应过程中平衡选择的重要性。
The distribution of fitness effects (DFE) among newly arisen mutations has critical implications for a wide range of research themes in evolutionary biology and quantitative genetics. While mathematical models have played an important role in predicting and interpreting empirical features of the DFE, the theory has largely ignored environmental heterogeneity, and the potential for genetic tradeoffs for fitness between environmental contexts that are relevant to single populations. Environmental change can alter the genetic basis of fitness over time or space by way of two possible routes: (1) by altering the orientation of natural selection; and (2) by altering the phenotypes expressed by a given genotype (i.e., phenotypic plasticity). While both phenomena are widely observed in nature, their implications for the DFE have yet to be incorporated within a formal model. Here, we develop an extension of Fisher’s geometric model that explicitly considers the relative impact of fluctuating selection and plasticity on the DFE. We show that environmental heterogeneity generally exacerbates evolutionary constraints by reducing the fraction of mutations that are beneficial, and increasing the pervasiveness of fitness tradeoffs between environmental contexts. In this sense, environmental heterogeneity and pleiotropy have analogous effects on adaptation. We demonstrate that heterogeneity – like pleiotropy – constrains the range of genetic pathways that are accessible to adaptive evolution, and increases the importance of balancing selection during adaptation.