INVARIANT PER-GENOME MUTATION RATES

在20世纪60年代末，来自几个实验室的当时可用的数据 表明微生物表现出恒定的正向突变率 每一次复制0.003个基因组；基因组大小变化约1000倍， 相反，每一次复制的每个碱基对的突变率也是如此。这 观察表明，突变率已经进化到了一个最优水平 令人惊讶的是在不同的生物体中保持不变。从那时起， 已发布的数据库对许多生物体进行了改进，并使其不变性 每个基因组的突变率似乎不仅仍然是常态，而且 从含有单链DNA的噬菌体一直延伸到 微生物真核生物。然而，RNA病毒和后生动物似乎拥有 突变率与基于DNA的微生物的突变率有很大不同。

In the late 1960s the then-available data from several laboratories suggested that microbes exhibited a constant forward mutation rate of about 0.003 per genome per replication; genome sizes varied by about 1000-fold, and so, inversely, did mutation rates per base pair per replication. This observation suggested that mutation rates had evolved to an optimum that was surprisingly constant among diverse organisms. Since then, the published data base has improved for many organisms and the invariance of per-genome mutation rates appears not only still to be the norm, but to extend all the way from a bacteriophage containing single-stranded DNA to microbial eukaryotes. However, RNA viruses and metazoans appear to possess mutation rates quite different from those of DNA-based microbes.