A rheostat model for a rapid and reversible form of imprinting-dependent evolution
A rheostat model for a rapid and reversible form of imprinting-dependent evolution
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DOI：
10.1086/340969
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发表时间：
2002-06-01
影响因子：
9.8
通讯作者：
Jiang, YH
中科院分区：
文献类型：
--
作者：
Beaudet, AL;Jiang, YH
基因组印记的进化优势令人费解。我们认为，基因组印迹进化为一种机制，可以最大化剂量敏感基因座的基因表达速率的个体间变异性，以最小的无关有害影响，可以在广泛的连续体中改变表型。我们假设(1)基因组印迹提供了先前提出的单倍体选择优势(HSA)；(2)许多印迹基因已经进化出促进基因表达的数量超变量(QH)的机制；(3)HSA和QH的结合使得能够调节表型变化的快速和可逆形式的印迹依赖进化(IDE)成为可能；以及(4)这种对不断变化的环境的增强的适应性为种群提供了选择性优势，作为一种辅助形式的进化。这些机制可能为哺乳动物基因组印记的进化提供了至少一个驱动力。变阻器模型表明，遗传和表观遗传变异都可以促进孟德尔和非孟德尔混合遗传的综合机制，并表明大多数变异本质上不是有害的，但取决于环境，每个变异都是潜在的有利因素。此外，这将是一种可逆的进化形式，不仅能够保护沉默的等位基因在许多世代中不被选择，而且能够在种群中迅速重新激活和扩大它。
The evolutionary advantages of genomic imprinting are puzzling. We propose that genomic imprinting evolved as a mechanism that maximizes the interindividual variability in the rates of gene expression for dosage-sensitive loci that, with minimal unrelated deleterious effects, can alter the phenotype over a wide continuum. We hypothesize (1) that genomic imprinting provides a previously suggested haploid selective advantage (HSA); (2) that many imprinted genes have evolved mechanisms that facilitate quantitative hypervariability (QH) of gene expression; (3) that the combination of HSA and QH makes possible a rapid and reversible form of imprinting-dependent evolution (IDE) that can mediate changes in phenotype; and (4) that this enhanced adaptability to a changing environment provides selective advantage to the population, as an assisted form of evolution. These mechanisms may have provided at least one of the driving forces for the evolution of genomic imprinting in mammals. The rheostat model suggests that both genetic and epigenetic variants can contribute to an integrated mechanism of mixed Mendelian and non-Mendelian inheritance and suggests the possibility that the majority of variants are not intrinsically deleterious but, depending on the environment, are each potentially advantageous. Moreover, this would be a reversible form of evolution, with the ability not only to protect a silent allele from selection for many generations but to reactivate and expand it in the population quickly.