A study on a nearly neutral mutation model in finite populations.
A study on a nearly neutral mutation model in finite populations.
复制标题
有限种群中近中性突变模型的研究。
作者：
H. Tachida
作为一种接近中性的突变模型，我们利用计算机模拟研究了有限种群中的纸牌屋模型。突变效应的分布假定为正态分布。该行为主要由种群大小N与突变效应分布的标准差sigma的乘积决定。如果4N比1大，一些有利的突变就会在早期几代中迅速固定下来。然后大多数突变变成有害的，平均选择系数的增长非常缓慢。总体需要很长时间才能达到平衡状态。等位基因的替换在后期很少发生。如果4N σ是1或更少的数量级，则行为在质量上与严格中性情况相似。平均选择系数逐渐增大，在突变率逆数倍的世代中，种群几乎达到平衡状态。有利的和中性的（包括轻微有害的）突变都是固定的。除早期外，突变效应分布标准差的增加使平均杂合度降低。取代率随着4N的增加而降低。三个中性检验，一个使用平均杂合度与方差之间的关系，另一个使用平均杂合度与平均替换数之间的关系，以及沃森纯合度检验，应用于本模型的结果。发现只有当4N σ大于2时，中性期望的偏差才会变得明显。同时提出了一个简单的近似模型，当突变率很小时，该模型也能很好地工作。
As a nearly neutral mutation model, the house-of-cards model is studied in finite populations using computer simulations. The distribution of the mutant effect is assumed to be normal. The behavior is mainly determined by the product of the population size, N, and the standard deviation, sigma, of the distribution of the mutant effect. If 4N sigma is large compared to one, a few advantageous mutants are quickly fixed in early generations. Then most mutation becomes deleterious and very slow increase of the average selection coefficient follows. It takes very long for the population to reach the equilibrium state. Substitutions of alleles occur very infrequently in the later stage. If 4N sigma is the order of one or less, the behavior is qualitatively similar to that of the strict neutral case. Gradual increase of the average selection coefficient occurs and in generations of several times the inverse of the mutation rate the population almost reaches the equilibrium state. Both advantageous and neutral (including slightly deleterious) mutations are fixed. Except in the early stage, an increase of the standard deviation of the distribution of the mutant effect decreases the average heterozygosity. The substitution rate is reduced as 4N sigma is increased. Three tests of neutrality, one using the relationship between the average and the variance of heterozygosity, another using the relationship between the average heterozygosity and the average number of substitutions and Watterson's homozygosity test are applied to the consequences of the present model. It is found that deviation from the neutral expectation becomes apparent only when 4N sigma is more than two. Also a simple approximation for the model is developed which works well when the mutation rate is very small.
影响因子：
56.9
作者：
BOWIE, JU;REIDHAAROLSON, JF;SAUER, RT
通讯作者：
SAUER, RT
影响因子：
3.3
作者：
M. Kreitman;Montserrat Aguadé
通讯作者：
M. Kreitman;Montserrat Aguadé
影响因子：
3.3
作者：
Aquadro,CF;Lado,KM;Noon,WA
通讯作者：
Noon,WA