Department of Biology, Pomona College, 175 W 6th Street, Claremont, CA, USA.
J Mol Evol. 2013 Feb;76(1-2):71-80. doi: 10.1007/s00239-013-9542-7. Epub 2013 Jan 24.
The canonical code has been shown many times to be highly robust against point mutations; that is, mutations that change a single nucleotide tend to result in similar amino acids more often than expected by chance. There are two major types of models for the origin of the code, which explain how this sophisticated structure evolved. Adaptive models state that the primitive code was specifically selected for error minimization, while historic models hypothesize that the robustness of the code is an artifact or by-product of the mechanism of code evolution. In this paper, we evaluated the levels of robustness in existing non-canonical codes as well as codes that differ in only one codon assignment from the standard code. We found that the level of robustness of many of these codes is comparable or better than that of the standard code. Although these results do not preclude an adaptive origin of the genetic code, they suggest that the code was not selected for minimizing the effects of point mutations.
规范密码多次被证明对单点突变具有高度的鲁棒性；也就是说，改变单个核苷酸的突变往往比随机预期更常导致相似的氨基酸。有两种主要的密码起源模型，它们解释了这种复杂结构是如何进化的。适应性模型表明，原始密码是专门为最小化错误而选择的，而历史模型则假设密码的鲁棒性是密码进化机制的一种artifact 或副产品。在本文中，我们评估了现有非规范密码以及与标准密码仅在一个密码子赋值上不同的密码的鲁棒性水平。我们发现，这些密码中的许多密码的鲁棒性水平与标准密码相当或更好。尽管这些结果不能排除遗传密码的适应性起源，但它们表明代码不是为了最小化单点突变的影响而选择的。
