Clark A G
Department of Biology, Pennsylvania State University, University Park 16802.
Genetics. 1988 Jul;119(3):711-20. doi: 10.1093/genetics/119.3.711.
A theoretical population genetic model is developed to explore the consequences of X-Y recombination in the evolution of sex chromosome polymorphism. The model incorporates one sex-determining locus and one locus subject to natural selection. Both loci have two alleles, and the rate of classical meiotic recombination between the loci is r. The alleles at the sex-determining locus specify whether the chromosome is X or Y, and the alleles at the selected locus are arbitrarily labeled A and a. Natural selection is modeled as a process of differential viabilities. The system can be expressed in terms of three recurrence equations, one for the frequency of A on the X-bearing gametes produced by females, one for each of the frequency of A on the X- and Y-bearing gametes produced by males. Several special cases are examined, including X chromosome dominance and symmetric selection. Unusual equilibria are found with the two sexes having very different allele frequencies at the selected locus. A significant finding is that the allowance of recombination results in a much greater opportunity for polymorphism of the Y chromosome. Tighter linkage results in a greater likelihood for equilibria with a large difference between the sex chromosomes in allele frequency.
建立了一个理论群体遗传模型，以探讨X - Y重组在性染色体多态性进化中的后果。该模型纳入了一个性别决定位点和一个受自然选择影响的位点。两个位点都有两个等位基因，并且两个位点之间经典减数分裂重组的速率为r。性别决定位点的等位基因决定染色体是X还是Y，所选位点的等位基因被任意标记为A和a。自然选择被建模为一个差异生存能力的过程。该系统可以用三个递推方程来表示，一个用于雌性产生的携带X的配子上A的频率，一个用于雄性产生的携带X和携带Y的配子上A的频率。研究了几种特殊情况，包括X染色体显性和对称选择。发现了不寻常的平衡，即两性在所选位点具有非常不同的等位基因频率。一个重要的发现是，允许重组会为Y染色体多态性带来更大的机会。更紧密的连锁导致等位基因频率在性染色体之间有很大差异的平衡的可能性更大。
