Uyenoyama M K, Waller D M
Department of Zoology, Duke University, Durham, North Carolina 27706.
Theor Popul Biol. 1991 Aug;40(1):47-77. doi: 10.1016/0040-5809(91)90046-i.
We describe the evolutionary dynamics of a modifier of selfing coevolving with a locus subject to symmetric overdominance in viability under general levels of reduction in pollination success as a consequence of self-fertilization (pollen discounting). Simple models of the evolution of breeding systems that represent inbreeding depression as a constant parameter do not admit the possibility of stable mixed mating systems involving both inbreeding and random mating. Contrary to this expectation, we find that coevolution between a modifier of selfing and a single overdominant locus situated anywhere in the genome can generate evolutionarily attracting mixed mating systems. Two forms of association between the modifier locus and the viability locus promote the evolution of outcrossing. The favored heterozygous genotype at the viability locus develops positive associations with modifier alleles that enhance outcrossing and with the heterozygous genotype at the modifier locus. Associations between outcrossing and high viability evolve immediately upon the introduction of a rare modifier allele, even in the absence of linkage.
我们描述了在自花受精（花粉折扣）导致授粉成功率普遍降低的情况下，一个自交修饰因子与一个在生存力方面受对称超显性影响的基因座共同进化的进化动态。将近亲繁殖衰退表示为一个恒定参数的简单育种系统进化模型，不允许存在涉及近亲繁殖和随机交配的稳定混合交配系统的可能性。与这种预期相反，我们发现自交修饰因子与基因组中任何位置的单个超显性基因座之间的共同进化可以产生具有进化吸引力的混合交配系统。修饰因子基因座与生存力基因座之间的两种关联形式促进了异交的进化。在生存力基因座上受青睐的杂合基因型与增强异交的修饰因子等位基因以及修饰因子基因座上的杂合基因型形成正相关。即使在没有连锁的情况下，引入一个罕见的修饰因子等位基因后，异交与高生存力之间的关联也会立即进化。
