Hedrick P W
Department of Genetics, University of California, Berkeley 94720.
Genetics. 1987 Oct;117(2):331-41. doi: 10.1093/genetics/117.2.331.
Five different measures of gametic disequilibrium in current use and a new one based on R. C. Lewontin's D', are examined and compared. All of them, except the measure based on Lewontin's D', are highly dependent upon allelic frequencies, including four measures that are normalized in some manner. In addition, the measures suggested by A. H. D. Brown, M. F. Feldman and E. Nevo, and T. Ohta can have negative values when there is maximum disequilibrium and have rates of decay in infinite populations that are a function of the initial gametic array. The variances were large for all the measures in samples taken from populations at equilibrium under neutrality, with the measure based on D' having the lowest variance. In these samples, three of the measures were highly correlated, D2, D (equal to the correlation coefficient when there are two alleles at each locus) and the measure X(2) of Brown et al. Using frequency-dependent measures may result in mistaken conclusions, a fact illustrated by discussion of studies inferring recombinational hot spots and the effects of population bottlenecks from disequilibrium values.
对当前使用的五种不同的配子不平衡测量方法以及一种基于R.C. 莱温廷的D' 的新方法进行了检验和比较。除了基于莱温廷的D' 的方法外，所有其他方法都高度依赖等位基因频率，其中包括四种以某种方式进行了标准化的方法。此外，A.H.D. 布朗、M.F. 费尔德曼和E. 内沃以及T. 太田提出的方法在不平衡达到最大值时可能会出现负值，并且在无限种群中的衰减率是初始配子阵列的函数。对于从中性平衡种群中抽取的样本，所有测量方法的方差都很大，基于D' 的方法方差最小。在这些样本中，三种测量方法高度相关，即D2、D（当每个位点有两个等位基因时等于相关系数）以及布朗等人的X(2) 方法。使用依赖频率的测量方法可能会得出错误结论，通过讨论从不平衡值推断重组热点和种群瓶颈效应的研究可以说明这一事实。
