Di Chenlu, Lohmueller Kirk E
Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA.
Interdepartmental Program in Bioinformatics, University of California, Los Angeles, CA, USA.
Genome Biol Evol. 2024 Aug 5;16(8). doi: 10.1093/gbe/evae147.
Dominance refers to the effect of a heterozygous genotype relative to that of the two homozygous genotypes. The degree of dominance of mutations for fitness can have a profound impact on how deleterious and beneficial mutations change in frequency over time as well as on the patterns of linked neutral genetic variation surrounding such selected alleles. Since dominance is such a fundamental concept, it has received immense attention throughout the history of population genetics. Early work from Fisher, Wright, and Haldane focused on understanding the conceptual basis for why dominance exists. More recent work has attempted to test these theories and conceptual models by estimating dominance effects of mutations. However, estimating dominance coefficients has been notoriously challenging and has only been done in a few species in a limited number of studies. In this review, we first describe some of the early theoretical and conceptual models for understanding the mechanisms for the existence of dominance. Second, we discuss several approaches used to estimate dominance coefficients and summarize estimates of dominance coefficients. We note trends that have been observed across species, types of mutations, and functional categories of genes. By comparing estimates of dominance coefficients for different types of genes, we test several hypotheses for the existence of dominance. Lastly, we discuss how dominance influences the dynamics of beneficial and deleterious mutations in populations and how the degree of dominance of deleterious mutations influences the impact of inbreeding on fitness.
显性指的是杂合基因型相对于两种纯合基因型的效应。突变对适合度的显性程度会对有害和有益突变随时间推移在频率上的变化以及围绕此类被选择等位基因的连锁中性遗传变异模式产生深远影响。由于显性是如此基础的概念，在群体遗传学历史中它受到了极大关注。费希尔、赖特和霍尔丹早期的工作聚焦于理解显性存在的概念基础。近期的工作试图通过估计突变的显性效应来检验这些理论和概念模型。然而，估计显性系数一直极具挑战性，仅在少数物种的有限研究中得以完成。在本综述中，我们首先描述一些用于理解显性存在机制的早期理论和概念模型。其次，我们讨论用于估计显性系数的几种方法并总结显性系数的估计结果。我们指出在不同物种、突变类型和基因功能类别中观察到的趋势。通过比较不同类型基因的显性系数估计值，我们检验关于显性存在的几个假说。最后，我们讨论显性如何影响群体中有益和有害突变的动态变化，以及有害突变的显性程度如何影响近亲繁殖对适合度的影响。
