The distribution of gene frequencies in populations
The distribution of gene frequencies in populations
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DOI：
10.1126/science.85.2212.504
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发表时间：
1937-01-01
期刊：
影响因子：
56.9
通讯作者：
Wright, S
中科院分区：
文献类型：
--
作者：
Wright, S
各种进化因素的影响-突变，杂交育种，。选择和近亲繁殖--通过考虑它们倾向于在等位基因的相对频率中引起的变化率，可以被简化为普通术语。“在缺乏这些因素的情况下，孟德尔机制的对称性使基因频率保持恒定。给定基因的频率（q）在基因以速率u重复突变为等位基因的情况下，每代以速率Aq =-uq变化。以每代平均速率v的相反方向的突变以速率Aq = v（l-q）改变基因频率。如果某一基因在局部群体中的频率为q，而在整个物种中的频率为q1，则局部群体的比例m与来自整个物种的相同数量的随机个体的比例m的交换导致局部群体中基因频率的变化率Aq =-m（q-q，）。然而，杂交育种最有可能是与相邻的种群进行的，这些种群在q值上差异很小。在这种情况下，系数m只是实际交换量的一小部分。可能还有其他复杂的情况，如选择性迁入或迁出，但上述简单的形式在这里足以说明杂交育种或迁移压力，最简单的一种选择是，杂合子在每一个体对下一代的贡献程度上正好介于两个纯合子之间。合子的选择值（相对于某一标准）将被指定为w，群体的平均值为w。
The effects of the various evolutionary factors-mutation, cross breeding,. selection and inbreeding-can be reduced to common terms by con-sidering the rates of change which they tend to bring about in the relative frequencies of alleles.'In the absence of such factors, there is constancy of gene frequencies from the symmetry of the Mendelian mechanism. The frequency (q) of a given gene changes at the rate Aq=-uq per generation under recurrent mutation of the gene to alleles at the rate u. Mutation in the opposite direction at the average rate v per generation changes the gene frequency at the rate, Aq= v (l-q). If a certain gene has the frequency q in a local population but q1 in the species as a whole, exchange of the proportionm of the localpopulation with an equal number of random individuals from the whole species leads to change of gene frequencies in the former at the rate Aq=-m (q-q,). Cross breeding is, however, most likely to be with neighboringpopulations which differ but little in value of q. In this case the coefficient m isonly a small fraction of the actual amount of exchange. There may be other complications such as selective immigration or emigration, but the above simple form will suffice here to illustrate cross breeding or migration pressure.The simplest kind of selection is that in which the heterozygote is exactly half way between the two homozygotes in the extent per individual to which it contributes to the next generation. The selective value of zygotes (relative to a certain standard) will be designated w and the mean value for a population, w.