Drake J W
Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.
Proc Natl Acad Sci U S A. 1991 Aug 15;88(16):7160-4. doi: 10.1073/pnas.88.16.7160.
In terms of evolution and fitness, the most significant spontaneous mutation rate is likely to be that for the entire genome (or its nonfrivolous fraction). Information is now available to calculate this rate for several DNA-based haploid microbes, including bacteriophages with single- or double-stranded DNA, a bacterium, a yeast, and a filamentous fungus. Their genome sizes vary by approximately 6500-fold. Their average mutation rates per base pair vary by approximately 16,000-fold, whereas their mutation rates per genome vary by only approximately 2.5-fold, apparently randomly, around a mean value of 0.0033 per DNA replication. The average mutation rate per base pair is inversely proportional to genome size. Therefore, a nearly invariant microbial mutation rate appears to have evolved. Because this rate is uniform in such diverse organisms, it is likely to be determined by deep general forces, perhaps by a balance between the usually deleterious effects of mutation and the physiological costs of further reducing mutation rates.
就进化和适应性而言，最显著的自发突变率可能是整个基因组（或其非无足轻重的部分）的突变率。现在已有信息可用于计算几种基于DNA的单倍体微生物的这一速率，包括具有单链或双链DNA的噬菌体、一种细菌、一种酵母和一种丝状真菌。它们的基因组大小相差约6500倍。它们每碱基对的平均突变率相差约16000倍，而它们每个基因组的突变率仅相差约2.5倍，显然是随机的，围绕着每个DNA复制0.0033的平均值波动。每碱基对的平均突变率与基因组大小成反比。因此，一种近乎不变的微生物突变率似乎已经进化出来。由于这一速率在如此多样的生物体中是一致的，它很可能是由深层次的普遍力量决定的，也许是由突变通常产生的有害影响与进一步降低突变率的生理成本之间的平衡所决定的。
