University of Zurich Institute of Evolutionary Biology and Environmental Studies, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
Trends Genet. 2011 Oct;27(10):397-410. doi: 10.1016/j.tig.2011.06.002. Epub 2011 Aug 27.
The history of life is a history of evolutionary innovations, qualitatively new phenotypic traits that endow their bearers with new, often game-changing abilities. We know many individual examples of innovations and their natural history, but we know little about the fundamental principles of phenotypic variability that permit new phenotypes to arise. Most phenotypic innovations result from changes in three classes of systems: metabolic networks, regulatory circuits, and macromolecules. I here highlight two important features that these classes of systems share. The first is the ubiquity of vast genotype networks - connected sets of genotypes with the same phenotype. The second is the great phenotypic diversity of small neighborhoods around different genotypes in genotype space. I here explain that both features are essential for the phenotypic variability that can bring forth qualitatively new phenotypes. Both features emerge from a common cause, the robustness of phenotypes to perturbations, whose origins are linked to life in changing environments.
生命的历史是一个不断进化创新的历史，新的表型特征赋予了它们的承载者新的、常常是改变游戏规则的能力。我们知道许多创新的例子及其自然历史，但我们对允许新表型出现的表型可变性的基本原理知之甚少。大多数表型创新是由代谢网络、调控回路和大分子这三类系统的变化引起的。我在这里强调这三类系统所共有的两个重要特征。第一个是广泛存在的基因型网络——具有相同表型的基因型的连通集合。第二个是基因型空间中不同基因型周围的小邻域的巨大表型多样性。我在这里解释说，这两个特征对于能够产生新表型的表型可变性都是必不可少的。这两个特征都源于一个共同的原因，即表型对干扰的稳健性，其起源与在不断变化的环境中的生命有关。
