Nei M, Li W H
Genetics. 1973 Sep;75(1):213-9. doi: 10.1093/genetics/75.1.213.
The linkage disequilibrium in a subdivided populaton is shown to be equal to the sum of the average linkage disequilibrium for all subpopulations and the covariance between gene frequencies of the loci concerned. Thus, in a subdivided population the linkage disequilibrium may not be 0 even if the linkage disequilibrium in each subpopulation is 0. If a population is divided into two subpopulations between which migration occurs, the asymptotic rate of approach to linkage equilibrium is equal to either r or 2(m(1) + m(2)) - (m(1) + m(2))(2), whichever is smaller, where r is the recombination value and m(1) and m(2) are the proportions of immigrants in subpopulations 1 and 2, respectively. Thus, if migration rate is high compared with recombination value, the change of linkage disequilibrium in subdivided populations is similar to that of a single random mating population. On the other hand, if migration rate is low, the approach to lnkage equilibrium may be retarded in subdivided populations. If isolated populations begin to exchange genes by migration, linkage disequilibrium may increase temporarily even for neutral loci. If overdominant selection operates and the equilibrium gene frequencies are different in the two subpopulations, a permanent linkage disequilibrium may be produced without epistasis in each subpopulation.
在一个细分群体中，连锁不平衡被证明等于所有亚群体平均连锁不平衡之和以及相关位点基因频率之间的协方差。因此，在一个细分群体中，即使每个亚群体中的连锁不平衡为0，连锁不平衡也可能不为0。如果一个群体被分成两个有基因迁移的亚群体，达到连锁平衡的渐近速率等于r或2(m(1) + m(2)) - (m(1) + m(2))(2)中的较小值，其中r是重组值，m(1)和m(2)分别是亚群体1和2中移民的比例。因此，如果迁移率相对于重组值较高，细分群体中连锁不平衡的变化类似于单个随机交配群体的变化。另一方面，如果迁移率较低，细分群体中达到连锁平衡的过程可能会延迟。如果隔离群体开始通过迁移交换基因，即使对于中性位点，连锁不平衡也可能会暂时增加。如果存在超显性选择且两个亚群体中的平衡基因频率不同，那么在每个亚群体中没有上位性的情况下也可能产生永久的连锁不平衡。
