Weir B S, Hill W G
Program in Statistical Genetics, Department of Statistics, North Carolina State University, Raleigh, North Carolina 27695-7566, USA.
Annu Rev Genet. 2002;36:721-50. doi: 10.1146/annurev.genet.36.050802.093940. Epub 2002 Jun 11.
A moment estimator of, the coancestry coefficient for alleles within a population, was described by Weir & Cockerham in 1984 (100) and is still widely cited. The estimate is used by population geneticists to characterize population structure, by ecologists to estimate migration rates, by animal breeders to describe genetic variation, and by forensic scientists to quantify the strength of matching DNA profiles. This review extends the work of Weir & Cockerham by allowing different levels of coancestry for different populations, and by allowing non-zero coancestries between pairs of populations. All estimates are relative to the average value of theta between pairs of populations. Moment estimates for within- and between-population theta values are likely to have large sampling variances, although these may be reduced by combining information over loci. Variances also decrease with the numbers of alleles at a locus, and with the numbers of populations sampled. This review also extends the work of Weir & Cockerham by employing maximum likelihood methods under the assumption that allele frequencies follow the normal distribution over populations. For the case of equal theta values within populations and zero theta values between populations, the maximum likelihood estimate is the same as that given by Robertson & Hill in 1984 (70). The review concludes by relating functions of theta values to times of population divergence under a pure drift model.
1984年，韦尔和科克伦描述了群体中等位基因的共祖系数的矩估计量（100），至今仍被广泛引用。群体遗传学家用该估计量来描述群体结构，生态学家用它来估计迁移率，动物育种家用它来描述遗传变异，法医科学家用它来量化匹配DNA图谱的强度。本综述扩展了韦尔和科克伦的工作，允许不同群体有不同水平的共祖系数，并允许群体对之间的共祖系数不为零。所有估计都是相对于群体对之间θ的平均值而言的。群体内和群体间θ值的矩估计可能有较大的抽样方差，不过通过整合多个位点的信息可能会减小这些方差。方差也会随着一个位点上等位基因的数量以及所抽样群体的数量而减小。本综述还通过在等位基因频率在群体中呈正态分布的假设下采用最大似然法，扩展了韦尔和科克伦的工作。对于群体内θ值相等且群体间θ值为零的情况，最大似然估计与1984年罗伯逊和希尔给出的估计相同（70）。综述最后通过在纯漂变模型下将θ值的函数与群体分化时间联系起来得出结论。
