Heritable variation and heterozygosity under a balance between mutations and stabilizing selection.
Heritable variation and heterozygosity under a balance between mutations and stabilizing selection.
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突变和稳定选择之间的平衡下的遗传变异和杂合性。
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发表时间：
1987
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通讯作者：
M. Slatkin
中科院分区：
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作者：
M. Slatkin
摘要 开发并分析了影响数量特征的突变和稳定选择之间的平衡模型。该模型本质上是 Kimura、Lande、Turelli 等人之前分析的等位基因连续体模型的离散化版本，在形式上类似于用于解释电泳数据的逐步突变模型。即使对于单倍体物种也无法求解完整模型，但对于大多数感兴趣的参数值都有有用的近似值。当选择相对于突变较强时，可以使用“纸牌屋”近似，而当选择相对较弱时，可以使用正态近似。对于中间水平的选择，新的“五等位基因”近似可在各种参数值上提供准确的结果。应用于二倍体群体中隐性等位基因的纸牌屋和五等位基因近似表明，对于给定的突变率，与可比的加性等位基因模型相比，在平衡状态下保持了稍大的遗传方差。在定向选择下，对于大效应的等位基因，遗传方差的增加最大，而对于中效应或小效应的等位基因，遗传方差的增加要小得多。在稳定选择的平衡下，当每个突变具有相对较大的影响（纸牌屋近似）时，纯合子往往比杂合子具有更高的平均适应度，如果每个突变具有较小的影响（正态近似），则相反。
Summary A model of the balance between mutations and stabilizing selection affecting a quantitative character is developed and analysed. This model is essentially a discretized version of the continuum-of-alleles models analysed previously by Kimura, Lande, Turelli and others, and is formally similar to the stepwise mutation models used to interpret electrophoretic data. The complete model cannot be solved even for a haploid species, but there are useful approximations for most parameter values of interest. The 'house-of-cards' approximation can be used when selection is strong relative to mutation, and a normal approximation can be used when selection is relatively weak. For intermediate levels of selection a new ' five-allele' approximation provides accurate results over a wide range of parameter values. The house-of-cards and five-allele approximations applied to recessive alleles in a diploid population show that, for a given mutation rate, a somewhat larger genetic variance is maintained at equilibrium than in a comparable model of additive alleles. Under directional selection, the increase in genetic variance is largest for alleles of large effect and is much smaller for alleles of intermediate or small effect. At an equilibrium under stabilizing selection, homozygotes would tend to have a higher average fitness than heterozygotes when each mutation has a relatively large effect (the house-of-cards approximation), with the reverse if each mutation has a small effect (the normal approximation).