In this study, we consider admixed populations through their expected heterozygosity, a measure of genetic diversity. A population is termed admixed if its members possess recent ancestry from two or more separate sources. As a result of the fusion of source populations with different genetic variants, admixed populations can exhibit high levels of genetic diversity, reflecting contributions of their multiple ancestral groups. For a model of an admixed population derived from K source populations, we obtain a relationship between its heterozygosity and its proportions of admixture from the various source populations. We show that the heterozygosity of the admixed population is at least as great as that of the least heterozygous source population, and that it potentially exceeds the heterozygosities of all of the source populations. The admixture proportions that maximize the heterozygosity possible for an admixed population formed from a specified set of source populations are also obtained under specific conditions. We examine the special case of \(K=2\) source populations in detail, characterizing the maximal admixture in terms of the heterozygosities of the two source populations and the value of \(F_{ST}\) between them. In this case, the heterozygosity of the admixed population exceeds the maximal heterozygosity of the source groups if the divergence between them, measured by \(F_{ST}\), is large enough, namely above a certain bound that is a function of the heterozygosities of the source groups. We present applications to simulated data as well as to data from human admixture scenarios, providing results useful for interpreting the properties of genetic variability in admixed populations.

在这项研究中，我们通过其预期的杂合性（遗传多样性的衡量标准）来考虑混合种群。如果一个群体的成员拥有来自两个或多个不同来源的近期血统，则该群体被称为混合群体。由于源种群与不同遗传变异的融合，混合种群可以表现出高度的遗传多样性，反映了其多个祖先群体的贡献。对于从K导出的混合总体模型源种群，我们从各种源种群中获得其杂合度与其混合比例之间的关系。我们表明，混合种群的杂合度至少与杂合最少的源种群的杂合度一样大，并且它可能超过所有源种群的杂合度。也可以在特定条件下获得使由一组指定源种群形成的混合种群的可能杂合性最大化的混合比例。我们详细检查了\(K=2\)源种群的特殊情况，根据两个源种群的杂合度和\(F_{ST}\)的值来表征最大混合它们之间。在这种情况下，如果通过\(F_{ST}\)测量的它们之间的差异足够大，即高于作为源组的杂合性。我们展示了模拟数据以及来自人类混合场景的数据的应用，提供了有助于解释混合种群遗传变异特性的结果。