Bacteria that cause serious disease often have smaller genomes, and fewer genes, than their nonpathogenic, or less pathogenic relatives. Here, we review evidence for the generality of this association, and summarise the various reasons why the association might hold. We focus on the population genetic processes that might lead to reductive genome evolution, and show how several of these could be connected to pathogenicity. We find some evidence for most of the processes having acted in bacterial pathogens, including several different modes of genome reduction acting in the same lineage. We argue that predictable processes of genome evolution might not reflect any common underlying process.

与非致病性或致病性较低的亲属相比，引起严重疾病的细菌通常具有较小的基因组和较少的基因。在这里，我们回顾了这种关联的普遍性的证据，并总结了可能成立这种关联的各种原因。我们关注可能导致还原性基因组进化的种群遗传过程，并展示其中的几种可能与致病性有关。我们发现了对细菌病原体起作用的大多数过程的一些证据，包括在同一谱系中起作用的几种不同的基因组还原模式。我们认为基因组进化的可预测过程可能无法反映任何常见的潜在过程。