The evolution of cytidine deaminases capable of generating genetic diversity by editing nucleic acids

遗传多样性是群体中个体的区别。它对于允许物种在环境条件变化中生存具有根本的重要性。这适用于试图逃避免疫反应的病毒，任何受到病原体威胁的物种，面临饥饿或抗生素的细菌种群，甚至是肿瘤内竞争有限营养的癌细胞，仅举几例。遗传多样性通常是在复制细胞遗传物质的过程中，由于未纠正的错误，多年来缓慢积累的。然而，一些物种已经获得了通过主动产生和容忍突变来提高这些变化发生率的机制。由于高突变率也可能是有害的（导致死亡或肿瘤），这些机制并不总是活跃的，但通常由压力或感染引起。

Genetic diversity differentiates individuals within a population. It has fundamental importance in allowing a species to survive to changes in environmental conditions. This is applicable to a virus trying to escape an immune response, to any species under the threat of a pathogen, to bacterial populations facing starvation or antibiotics, or even to cancer cells within a tumor competing for limited nutrients, to name just a few. Genetic diversity normally accumulates slowly over the years from uncorrected mistakes at replicating the cell's genetic material. However, some species have acquired mechanisms to boost the rate with which these changes occur by having ways of actively producing and tolerating mutations. Since high mutation rates can also be detrimental (cause death or tumors) these mechanisms are not always active but usually induced by stress or infection.