Data from: Progressive genome-wide introgression in agricultural Campylobacter coli

Hybridization between distantly related organisms can facilitate rapid adaptation to novel environments, but is potentially constrained by epistatic fitness interactions among cell components. The zoonotic pathogens Campylobacter coli and C. jejuni differ from each other by around 15% at the nucleotide level, corresponding to an average of nearly 40 amino acids per protein-coding gene. Using whole genome sequencing, we show that a single C. coli lineage, which has successfully colonized an agricultural niche, has been progressively accumulating C. jejuni DNA. Members of this lineage belong to two groups, the ST-828 and ST-1150 clonal complexes. The ST-1150 complex is less frequently isolated and has undergone a substantially greater amount of introgression leading to replacement of up to 23% of the C. coli core genome as well as import of novel DNA. By contrast, the more commonly isolated ST-828 complex bacteria have 10–11% introgressed DNA, and C. jejuni and nonagricultural C. coli lineages each have <2%. Thus, the C. coli that colonize agriculture, and consequently cause most human disease, have hybrid origin, but this cross-species exchange has so far not had a substantial impact on the gene pools of either C. jejuni or nonagricultural C. coli. These findings also indicate remarkable interchangeability of basic cellular machinery after a prolonged period of independent evolution.远缘生物间的杂交可助力其快速适应全新环境，但细胞组分间的上位性适合度相互作用可能对该过程形成约束。人畜共患病原菌结肠弯曲杆菌（Campylobacter coli）与空肠弯曲杆菌（Campylobacter jejuni）在核苷酸水平上的差异约为15%，对应每个蛋白编码基因平均存在近40个氨基酸位点的差异。本研究借助全基因组测序技术证实，一个成功定殖于农业生态位的结肠弯曲杆菌谱系，正逐步累积空肠弯曲杆菌的DNA序列。该谱系包含两个类群：ST-828与ST-1150克隆复合体（clonal complex）。其中ST-1150复合体的分离频率较低，但其经历的基因渐渗（introgression）程度显著更高：其基因组中多达23%的结肠弯曲杆菌核心基因组（core genome）被替换，同时还导入了全新的DNA序列。与之形成对比的是，分离频率更高的ST-828复合体仅携带10%~11%的渐渗DNA序列，而空肠弯曲杆菌及非农业生态位结肠弯曲杆菌谱系的渐渗DNA占比均低于2%。由此可见，定殖于农业生态位并因此引发绝大多数人类感染病例的结肠弯曲杆菌，其起源具有杂交特性；但截至目前，这种跨物种基因交换并未对空肠弯曲杆菌或非农业生态位结肠弯曲杆菌的基因库（gene pool）造成显著影响。本研究结果同时表明，即便经历了长期的独立进化，基础细胞机器（cellular machinery）仍具有显著的可互换性。