THE DIVERGENCE OF A POLYGENIC SYSTEM SUBJECT TO STABILIZING SELECTION, MUTATION AND DRIFT
THE DIVERGENCE OF A POLYGENIC SYSTEM SUBJECT TO STABILIZING SELECTION, MUTATION AND DRIFT
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DOI：
10.1017/s0016672300028378
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发表时间：
1989-08-01
影响因子：
1.5
通讯作者：
BARTON, N
中科院分区：
文献类型：
--
作者：
BARTON, N
多基因变异可以通过突变和稳定选择之间的平衡来维持。当导致变异的等位基因很少时，许多类的平衡可能是稳定的。通过整合基因频率分布来研究漂变导致平衡间转移的速率。W2N .PI。(pq) 4 n.mu.-1。这个积分可以通过数值积分精确地找到，或者可以通过假设等位基因频率的完整分布近似为高斯分布来近似求得。这些方法是通过模拟来验证的。在很大的种群规模范围内，漂变将使种群保持在一个接近平衡的状态，从而使遗传变异和对选择最优的偏离最小化。如果种群规模和每个位点上的选择的乘积很小（n . α），这类均衡之间的转移就会以可观的速率发生。2 < 10)。即使底层分布严重偏斜，高斯近似也是准确的。生殖隔离随着种群向新的等位基因组合的转变而发展：然而，这一过程是缓慢的，在小种群中接近中性比率（.apprxeq. .mu.）。
Polygenic variation can be maintained by a balance between mutation and stabilizing selection. When the alleles responsible for variation are rare, many classes of equilibria may be stable. The rate at which drift causes shifts between equilibria is investigated by integrating the gene frequency distribution .hivin.W2N .PI. (pq)4N.mu.-1. This integral can be found exactly, by numerical integration, or can be approximated by assuming that the full distribution of allele frequencies is approximately Gaussian. These methods are checked against simulations. Over a wide range of population sizes, drift will keep the population near an equilibrium which minimizes the genetic variance and the deviation from the selective optimum. Shifts between equilibria in this class occur at an appreciable rate if the product of population size and selection on each locus is small (Ns.alpha.2 < 10). The Gaussian approximation is accurate even when the underlying distribution is strongly skewed. Reproductive isolation evolves as populations shift to new combinations of alleles: however, this process is slow, approaching the neutral rate (.apprxeq. .mu.) in small populations.