Korol Abraham B, Kirzhner Valery M, Ronin Yeafim I, Nevo Eviatar
Institute of Evolution, University of Haifa, Mount Carmel, Haifa, 31905, Israel.
Evolution. 1996 Aug;50(4):1432-1441. doi: 10.1111/j.1558-5646.1996.tb03917.x.
The subject of this paper is polymorphism maintenance due to stabilizing selection with a moving optimum. It was shown that in case of two-locus additive control of the selected trait, global polymorphism is possible only when the geometric mean fitnesses of double homozygotes averaged over the period are lower than that of the single heterozygotes and of the double heterozygote (with a multiplier [1 - r] , which depends on recombination rate r and period length p). But local stability of polymorphism cannot be excluded even if geometric mean fitnesses of all double homozygotes are higher than that of all heterozygotes. We proved, that for logarithmically convex fitness functions, cyclical changes of the optimum cannot help in polymorphism maintenance in case of additive control of the selected trait by two equal loci. However, within the same class of fitness functions, nonequal gene action and/or dominance effect for one or both loci may lead to local polymorphism stability with large enough polymorphism attracting domain. The higher the intensity of selection and closer the linkage between selected loci the larger is this domain. Note that even simple cyclical selection could result in two forms of polymorphic limiting behavior: (a) usually expected forced cycle with a period equal to that of environmental changes; and (b) "supercycles," nondumping auto-oscillations with a period comprising of hundreds of forced oscillation periods.
本文的主题是由于具有移动最优值的稳定选择而导致的多态性维持。结果表明，在所选择性状的双位点加性控制情况下，仅当在该时期内平均的双纯合子的几何平均适合度低于单杂合子和双杂合子的几何平均适合度时（乘以一个取决于重组率r和周期长度p的乘数[1 - r]），全局多态性才有可能。但是，即使所有双纯合子的几何平均适合度高于所有杂合子的几何平均适合度，也不能排除多态性的局部稳定性。我们证明，对于对数凸适合度函数，在所选择性状由两个相等位点进行加性控制的情况下，最优值的周期性变化无助于多态性维持。然而，在同一类适合度函数中，一个或两个位点的不等基因作用和/或显性效应可能导致具有足够大多态性吸引域的局部多态性稳定性。选择强度越高且所选位点之间的连锁越紧密，该域就越大。请注意，即使是简单的周期性选择也可能导致两种形式的多态性极限行为：(a)通常预期的强迫周期，其周期等于环境变化的周期；以及(b)“超周期”，即具有由数百个强迫振荡周期组成的周期的非衰减自振荡。
