Wagner Andreas
Department of Biology, 167 Castetter Hall, The University of New Mexico, Albuquerque, NM 87131, USA.
FEBS Lett. 2005 Mar 21;579(8):1772-8. doi: 10.1016/j.febslet.2005.01.063.
Biological systems, from macromolecules to whole organisms, are robust if they continue to function, survive, or reproduce when faced with mutations, environmental change, and internal noise. I focus here on biological systems that are robust to mutations and ask whether such systems are more or less evolvable, in the sense that they can acquire novel properties. The more robust a system is, the more mutations in it are neutral, that is, without phenotypic effect. I argue here that such neutral change--and thus robustness--can be a key to future evolutionary innovation, if one accepts that neutrality is not an essential feature of a mutation. That is, a once neutral mutation may cause phenotypic effects in a changed environment or genetic background. I argue that most, if not all, neutral mutations are of this sort, and that the essentialist notion of neutrality should be abandoned. This perspective reconciles two opposing views on the forces dominating organismal evolution, natural selection and random drift: neutral mutations occur and are especially abundant in robust systems, but they do not remain neutral indefinitely, and eventually become visible to natural selection, where some of them lead to evolutionary innovations.
从大分子到整个生物体的生物系统，如果在面对突变、环境变化和内部噪声时仍能继续发挥功能、存活或繁殖，那么它们就是稳健的。我在此关注对突变具有稳健性的生物系统，并探讨这类系统在获得新特性的意义上，其进化能力是更强还是更弱。一个系统越稳健，其中的中性突变就越多，也就是说，这些突变没有表型效应。我在此论证，如果人们接受中性并非突变的本质特征，那么这种中性变化——进而稳健性——可能是未来进化创新的关键。也就是说，一个曾经的中性突变在变化的环境或遗传背景中可能会产生表型效应。我认为，即使不是所有的中性突变，大多数也是这种情况，而且中性的本质主义观念应该被摒弃。这一观点调和了关于主导生物体进化的力量的两种对立观点，即自然选择和随机漂变：中性突变会发生，并且在稳健系统中尤其丰富，但它们不会永远保持中性，最终会被自然选择所察觉，其中一些会导致进化创新。
