Genetic and statistical analyses of strong selection on polygenic traits: what, me normal?
Genetic and statistical analyses of strong selection on polygenic traits: what, me normal?
复制标题
多基因性状强选择的遗传和统计分析：什么，我正常吗？
作者：
M. Turelli;N. Barton
我们开发了一个一般群体遗传框架，用于分析多个位点上的选择，并将其应用于加性多基因性状的强截断和破坏性选择。我们首先提出了统计方法来分析无穷小模型，其中后代育种值正态分布在父母的平均值周围，具有固定的方差。这些表明，通常假设的高斯分布的育种值在人口中给出了非常准确的预测的均值和方差，即使破坏性选择产生的显着偏离正态分布。然后，我们阐述了选择和重组的一般遗传分析。群体由描述单倍体基因型分布的多位点累积量表示，选择由平均适合度与这些累积量之间的关系描述。我们提供确切的递归生成函数的选择对非中心时刻的影响。重组的影响被简单地计算为减数分裂产生的所有排列的加权和。最后，新的累积量，描述下一代计算的非中心矩。虽然这个方案在这里只详细地应用于加性性状的选择，但它是相当普遍的。对于任意上位性和连锁，我们描述了一个一致的无穷小的限制，其中的短期选择反应占主导地位的无穷小的等位基因频率的变化和连锁不平衡。数值多位点的结果表明，标准高斯近似的平均值和遗传方差在此限制的动态给出了准确的预测。即使在强烈的截断选择下，三阶或更高阶的连锁不平衡也不会导致偏离正态性太多。因此，人工选择的预测和观察到的反应之间经常发现的经验偏差不是由联系不平衡引起的偏离常态。破坏性选择可以产生大量的四向不平衡，因此峰度;但即使这样，高斯假设预测的方差准确。与无穷小极限的明显简单性相反，数据表明，经过10代或更多代选择后，遗传方差的变化很可能是由依赖于遗传细节的等位基因频率动态所主导的。
We develop a general population genetic framework for analyzing selection on many loci, and apply it to strong truncation and disruptive selection on an additive polygenic trait. We first present statistical methods for analyzing the infinitesimal model, in which offspring breeding values are normally distributed around the mean of the parents, with fixed variance. These show that the usual assumption of a Gaussian distribution of breeding values in the population gives remarkably accurate predictions for the mean and the variance, even when disruptive selection generates substantial deviations from normality. We then set out a general genetic analysis of selection and recombination. The population is represented by multilocus cumulants describing the distribution of haploid genotypes, and selection is described by the relation between mean fitness and these cumulants. We provide exact recursions in terms of generating functions for the effects of selection on non-central moments. The effects of recombination are simply calculated as a weighted sum over all the permutations produced by meiosis. Finally, the new cumulants that describe the next generation are computed from the non-central moments. Although this scheme is applied here in detail only to selection on an additive trait, it is quite general. For arbitrary epistasis and linkage, we describe a consistent infinitesimal limit in which the short-term selection response is dominated by infinitesimal allele frequency changes and linkage disequilibria. Numerical multilocus results show that the standard Gaussian approximation gives accurate predictions for the dynamics of the mean and genetic variance in this limit. Even with intense truncation selection, linkage disequilibria of order three and higher never cause much deviation from normality. Thus, the empirical deviations frequently found between predicted and observed responses to artificial selection are not caused by linkage-disequilibrium-induced departures from normality. Disruptive selection can generate substantial four-way disequilibria, and hence kurtosis; but even then, the Gaussian assumption predicts the variance accurately. In contrast to the apparent simplicity of the infinitesimal limit, data suggest that changes in genetic variance after 10 or more generations of selection are likely to be dominated by allele frequency dynamics that depend on genetic details.
在强稳定选择下维持遗传变异：双基因座模型。
影响因子：
3.3
作者：
Gavrilets,S;Hastings,A
通讯作者：
Hastings,A
猪笼草蚊子 Wyeomyia smithii 种群之间光周期现象的上位性和遗传差异。
影响因子：
3.3
作者：
Hard,JJ;Bradshaw,WE;Holzapfel,CM
通讯作者：
Holzapfel,CM