The population genetic theory of hidden variation and genetic robustness
The population genetic theory of hidden variation and genetic robustness
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DOI：
10.1534/genetics.104.029173
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发表时间：
2004-12-01
期刊：
影响因子：
3.3
通讯作者：
Wagner, GP
中科院分区：
文献类型：
--
作者：
Hermisson, J;Wagner, GP
传递遗传学最可靠的概括之一是，携带主要突变的种群的表型变异相对于野生型增加。这种较高的变异至少有一部分是遗传的，是由于先前隐藏的变异释放出来的。同样，充满压力的环境也会导致隐性变异的表达。这两个观察结果被认为是野生型已经进化出抗遗传变异的稳健性的证据，即遗传管道化。在本文中，我们提出了在稳定选择下，一个主要突变或新环境与数量性状的加性遗传基础相互作用的一般模型。我们引入了突变-选择-漂移平衡中遗传方差的近似，其中包括之前使用的随机高斯近似和纸牌屋近似作为极限情况。然后我们发现，隐藏遗传变异的释放是具有上位性或基因型-环境相互作用的模型的一个普遍特性，无论是否对野生型基因型进行了分析。因此。即使突变体的性状状态与野生型性状一样健壮，可加性遗传变异也会随着环境或遗传背景的变化而增加。估计表明，这种预测的增加可能是相当可观的，特别是在大群体中，如果该性状的基因座上存在条件中性等位基因。对相关文献的简要回顾表明，该模型的假设可能适用于多基因性状。我们得出的结论是，由于重大突变或环境胁迫而释放的隐藏遗传变异并不表明野生型基因型的管道化。
One of the most solid generalizations of transmission genetics is that the phenotypic variance of populations carrying a major mutation is increased relative to the wild type. At least some part of this higher variance is genetic and due to release of previously hidden variation. Similarly, stressfull environments also lead to the expression of hidden variation. These two observations have been considered as evidence that the wild type has evolved robustness against genetic variation, i.e. genetic canalization. In this article we present a general model for the interaction of a major mutation or a novel environment with the additive genetic basis of a quantitative character under stabilizing selection. We introduce an approximation to the genetic variance in mutation-selection-drift balance that includes the previously used stochastic Gaussian and house-of-cards approximations as limiting cases. We then show that the release of hidden genetic variation is a generic property of models with epistasis or genotype-environment interaction, reregardless of whether the wild-type genotype is canalized or not. As a consequence. the additive genetic variance increases upon a change in the environment or the genetic background even if the mutant character state is as robust as the wild-type character. Estimates show that this predicted increase can be considerable, in particular in large populations and if there are conditionally neutral alleles at the loci underlying the trait. A brief review of the relevant literature suggests that the assumptions of this model are likely to be generic for polygenic traits. We conclude that the release of hidden genetic variance due to a major mutation or environmental stress does not demonstrate canalization of the wild-type genotype.