EFFECT OF SELECTION ON GENETIC VARIABILITY
EFFECT OF SELECTION ON GENETIC VARIABILITY
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DOI：
10.1086/282718
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发表时间：
1971-01-01
影响因子：
2.9
通讯作者：
BULMER, MG
中科院分区：
文献类型：
--
作者：
BULMER, MG
如果一个度量性状是由实际上无限数量的位点决定的，那么选择就不能在遗传变异中引起任何永久的变化，而是会引起暂时的变化，这种变化在选择停止时迅速逆转。这种变化完全是由于基因座对之间的相关性，这是由选择引起的；在稳定选择或定向选择下，相关性为负，导致遗传方差减小；在破坏性选择下，相关性为正，导致遗传方差增加。当选择停止时，随着基因座对的联合平衡重新建立，相关性迅速消失，方差恢复到原始值。在没有连锁的情况下，由于不平衡导致的遗传变异的预测变化量推导出了一个表达式。在自然条件下的选择强度下，这种变化可能很小，但在激烈的人工选择下，这种变化可能是可观的。这一限制性结果表明，由于选择导致的任何永久性方差变化的幅度必然随着涉及的基因座数量的增加而减小，并且当基因座数量很大时，它很可能远远小于由于不平衡引起的临时变化。
If a metric character is determined by an effectively infinite number of loci, selection cannot cause any permanent change in the genetic variance but will cause a temporary change which is rapidly reversed when selection ceases. This change is due entirely to the correlation between pairs of loci which is induced by selection; the correlation is negative, leading to a reduction in the genetic variance under stabilizing or directional selection, and is positive, leading to an increase in the variance under disruptive selection. When selection ceases, the correlation rapidly disappears as joint equilibrium at pairs of loci is reestablished, and the variance returns to its original value. An expression is derived for the predicted amount of change in the genetic variance due to disequilibrium in the absence of linkage. The change is likely to be small under selection intensities found under natural conditions, but it may be appreciable under intense artificial selection. This limiting result shows that the magnitude of any permanent change in the variance due to selection must decrease as the number of loci involved increases and that, when the number of loci is large, it is likely to be much less than the temporary change due to disequilibrium.