Pearce G P, Spencer H G
Department of Mathematics and Statistics, University of Waikato, Hamilton, New Zealand.
Genetics. 1992 Apr;130(4):899-907. doi: 10.1093/genetics/130.4.899.
The phenomenon of genomic imprinting has recently excited much interest among experimental biologists. The population genetic consequences of imprinting, however, have remained largely unexplored. Several population genetic models are presented and the following conclusions drawn: (i) systems with genomic imprinting need not behave similarly to otherwise identical systems without imprinting; (ii) nevertheless, many of the models investigated can be shown to be formally equivalent to models without imprinting; (iii) consequently, imprinting often cannot be discovered by following allele frequency changes or examining equilibrium values; (iv) the formal equivalences fail to preserve some well known properties. For example, for populations incorporating genomic imprinting, parameter values exist that cause these populations to behave like populations without imprinting, but with heterozygote advantage, even though no such advantage is present in these imprinting populations. We call this last phenomenon "pseudoheterosis." The imprinting systems that fail to be formally equivalent to nonimprinting systems are those in which males and females are not equivalent, i.e., two-sex viability systems and sex-chromosome inactivation.
基因组印记现象最近引起了实验生物学家的极大兴趣。然而，印记的群体遗传后果在很大程度上仍未得到探索。本文提出了几种群体遗传模型，并得出以下结论：（i）具有基因组印记的系统不一定与没有印记的相同系统表现相似；（ii）然而，许多研究的模型可以证明在形式上等同于没有印记的模型；（iii）因此，印记通常无法通过追踪等位基因频率变化或检查平衡值来发现；（iv）形式上的等效性未能保留一些众所周知的特性。例如，对于包含基因组印记的群体，存在一些参数值，这些参数值会使这些群体的行为类似于没有印记但具有杂合子优势的群体，即使这些印记群体中不存在这种优势。我们将最后这种现象称为“假杂种优势”。那些在形式上不等同于非印记系统的印记系统是指雄性和雌性不等同的系统，即两性生存能力系统和性染色体失活。
