Estimators for pairwise relatedness and individual inbreeding coefficients
Estimators for pairwise relatedness and individual inbreeding coefficients
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DOI：
10.1017/s0016672300033620
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发表时间：
1996-04-01
影响因子：
1.5
通讯作者：
Ritland, K
中科院分区：
文献类型：
--
作者：
Ritland, K
描述了两基因亲缘系数和近交系数以及四基因Cotterman系数的矩估计器。这些估计器使用共显性遗传标记，最适合估计成对亲缘关系或个体近亲交配系数，而不是它们在群体中的平均值。这是因为，与最大似然估计(MLE)相比，它们显示出更少的小样本偏差，并且缺乏分布假设。“有效”MME是每个基因座上每个等位基因给出的估计值的最优加权平均值。一般来说，权重必须用数值计算，但如果真系数设为零，则可得到相对效率相当高的简化估计器。假设在一个较大的参考群体样本中分析群体基因频率，并讨论了小参考样本引入的偏差和/或参考群体的遗传漂移。个体水平对亲缘关系或近亲交配的估计，虽然显示出高方差，但在人口研究中作为协变量在几个应用中是有用的。
Method-of-moments estimators (MMEs) for the two-gene coefficients of relationship and inbreeding, and for the four-gene Cotterman coefficients, are described. These estimators, which use co-dominant genetic markers, are most appropriate for estimating pairwise relatedness or individual inbreeding coefficients, as opposed to their mean values in a group. This is because, compared to the maximum likelihood estimate (MLE), they show reduced small-sample bias and lack distributional assumptions. The 'efficient' MME is an optimally weighted average of estimates given by each allele at each locus. Generally, weights must be computed numerically, but if true coefficients are assumed zero, simplified estimators are obtained whose relative efficiencies are quite high. Population gene frequency is assumed to be assayed in a larger, 'reference population' sample, and the biases introduced by small reference samples and/or genetic drift of the reference population are discussed. Individual-level estimates of relatedness or inbreeding, while displaying high variance, are useful in several applications as a covariate in population studies.