摘要：隐性遗传源自突变的表型稳定性，在指定的遗传环境背景下，它对表型没有影响，但是在发生突变以后或者环境发生了变化之后，它就会影响到表型。该研究显示：相对于那些没有隐性遗传的RNA酶，积累了隐性遗传的RNA酶可以更迅速的适应一种新的底物。
被称为“隐性突变”的一些突变对某一生物的表现型没有可以观察到的影响，除非它们与其他突变或环境变化相结合。由于最初的隐性变异在这种新条件下会变成有 益突变，所以曾有人提出，它也许能促进演化适应性，但由于自然基因组和环境的复杂性，这种观点并未通过实验得到严格的演示。在对试管中一个简化的体系（一 个单RNA酶的催化活性）所做的一项研究中，Andreas Wagner及其同事发现，已积累较多隐性变异的一个种群对一个新的化学环境的适应速度要快于变异较少的一个竞争种群。这样一个“适应前机制”的存在，对 于动物和植物育种、以及对于人类的复杂“性状疾病”(trait disease)都具有根本性的意义。
隐性遗传促使RNA酶迅速的进化
Cryptic variation is caused by the robustness of phenotypes to mutations. Cryptic variation has no effect on phenotypes in a given genetic or environmental background, but it can have effects after mutations or environmental change. Because evolutionary adaptation by natural selection requires phenotypic variation, phenotypically revealed cryptic genetic variation may facilitate evolutionary adaptation. This is possible if the cryptic variation happens to be pre-adapted, or “exapted”, to a new environment, and is thus advantageous once revealed. However, this facilitating role for cryptic variation has not been proven, partly because most pertinent work focuses on complex phenotypes of whole organisms whose genetic basis is incompletely understood. Here we show that populations of RNA enzymes with accumulated cryptic variation adapt more rapidly to a new substrate than a population without cryptic variation. A detailed analysis of our evolving RNA populations in genotype space shows that cryptic variation allows a population to explore new genotypes that become adaptive only in a new environment. Our observations show that cryptic variation contains new genotypes pre-adapted to a changed environment. Our results highlight the positive role that robustness and epistasis can have in adaptive evolution.
