Schnabel A, Asmussen M A
Department of Genetics, University of Georgia, Athens 30602.
Genetics. 1989 Sep;123(1):199-215. doi: 10.1093/genetics/123.1.199.
We define and determine the interrelationships among five sets of disequilibrium parameters that measure two- and three-locus nonrandom associations in nuclear-dicytoplasmic systems. These assume a diploid nuclear locus and two haploid cytoplasmic loci, with special reference to nuclear-mitochondrial-chloroplast systems. Three sets of two-locus disequilibria measure the association between haplotypes at the two cytoplasmic loci (DMC) and associations between each cytoplasmic locus and nuclear alleles or genotypes (DM, D1M, D2M, D3M; DC, D1C, D2C, D3C). In addition, we present two classes of higher-order disequilibria that measure nonrandom allelic or genotypic associations involving all three loci. The first class quantifies associations between the nuclear locus and the two cytoplasmic loci taken jointly (DA/MC, DAA/MC, DAa/MC, Daa/MC, etc.), whereas the second measures only those associations remaining after all two-locus associations have been taken into account (DA/M/C, DAA/M/C, DAa/M/C, Daa/M/C). Based on combinations of these five sets of measures, we suggest a variety of parameterizations of three-locus, nuclear-dicytoplasmic systems. The dynamics of these disequilibria are then investigated under models of random and mixed mating, either with both cytoplasmic genomes inherited through the same parent or through opposite parents. Except for associations between the cytoplasmic haplotypes, which are constant when the two cytoplasmic genomes are inherited through the same parent, all disequilibria ultimately decay to zero. These randomizations do not necessarily occur monotonically, however, and in some cases are preceded by an initial increase in magnitude or sign change. For both inheritance patterns, the asymptotic decay rates are steadily retarded by increasing levels of self-fertilization. This behavior contrasts with that in the extreme case of complete selfing, for which only the heterozygote disequilibria always decay to zero. For all models considered, the dynamics of the two-locus cytonuclear subsystems are solely a function of the mating system, whereas the dynamical behavior and sign patterns of the cytoplasmic and three-locus disequilibria also depend strongly on the mode of cytoplasmic inheritance.
我们定义并确定了五组不平衡参数之间的相互关系，这些参数用于衡量核 - 双细胞质系统中两位点和三位点的非随机关联。这些参数假定有一个二倍体核基因座和两个单倍体细胞质基因座，特别涉及核 - 线粒体 - 叶绿体系统。三组两位点不平衡参数衡量两个细胞质基因座上的单倍型之间的关联（DMC），以及每个细胞质基因座与核等位基因或基因型之间的关联（DM、D1M、D2M、D3M；DC、D1C、D2C、D3C）。此外，我们还提出了两类高阶不平衡参数，用于衡量涉及所有三个基因座的非随机关联或基因型关联。第一类参数量化核基因座与两个细胞质基因座联合起来的关联（DA/MC、DAA/MC、DAa/MC、Daa/MC等），而第二类仅衡量在考虑了所有两位点关联之后剩余的那些关联（DA/M/C、DAA/M/C、DAa/M/C、Daa/M/C）。基于这五组测量值的组合，我们提出了多种三位点核 - 双细胞质系统的参数化方法。然后，我们在随机交配和混合交配模型下研究这些不平衡参数的动态变化，这两种交配方式中细胞质基因组要么通过同一亲本遗传，要么通过相反的亲本遗传。除了细胞质单倍型之间的关联，当两个细胞质基因组通过同一亲本遗传时这种关联是恒定的，所有不平衡参数最终都会衰减至零。然而，这些随机化过程不一定是单调发生的，在某些情况下，在幅度或符号变化之前会有一个初始增加。对于这两种遗传模式，自交水平的增加会使渐近衰减率稳步减慢。这种行为与完全自交的极端情况不同，在完全自交的情况下，只有杂合子不平衡参数总是衰减至零。对于所考虑的所有模型，两位点细胞 - 核子系统的动态变化仅仅是交配系统的函数，而细胞质和三位点不平衡参数的动态行为及符号模式也强烈依赖于细胞质遗传模式。
