据4月11日的《科学》（Science）杂志报道说，新的研究显示，在动物肠道中存在的2个细菌品种正在融合成为另一种单独的品种。这一情况可能开始于牲畜的驯化过程，因为该过程使这两种细菌在鸡、牛及其它动物体内相遇。细菌间的基因交换是如此地频繁，因此很难为不同种类的细菌建立系谱，而我们对细菌自然群体的生态学知识尚处于初始阶段。虽然如此，空肠弯曲菌与大肠弯曲杆菌仍然被看作是截然不同的细菌品种，而这两种细菌是引起世界范围内人类胃肠道炎症的最常见的致病菌。
Samuel K. Sheppard及其同事对数个不同动物群体中的这2种细菌的基因序列进行了分析并得出结论，即这些细菌的基因已经混合到两种细菌的基因组正在合二为一的程度。文章的作者提出，先前存在于这两个品种之间的屏障可能已在新的环境中消失 — 假如是这样的话，按照进化论的说法，这种新的环境可能就是指在适于焙烤的嫩鸡或其它牲畜的肠道之内。（来源：EurekAlert!中文版）
两种细菌的基因在动物肠道内相混合。
（图片来源：Martin CJ Maiden）
（《科学》（Science），Vol. 320. no. 5873, pp. 237 - 239，Samuel K. Sheppard，Martin C. J. Maiden）
更多阅读（英文）
Convergence of Campylobacter Species: Implications for Bacterial Evolution
Samuel K. Sheppard, Noel D. McCarthy, Daniel Falush,* Martin C. J. Maiden
Samuel K. Sheppard, Noel D. McCarthy, Daniel Falush,* Martin C. J. Maiden
The nature of species boundaries in bacteria remains controversial. In particular, the mechanisms of bacterial speciation and maintenance in the face of frequent genetic exchange are poorly understood. Here, we report patterns of genetic exchange that show two closely related zoonotic pathogenic species, Campylobacter jejuni and Campylobacter coli, are converging as a consequence of recent changes in gene flow. Population expansion into a novel ecological niche generated by human activity is the most probable explanation for the increase in genetic exchange between these species. Bacterial speciation can therefore occur by mechanisms analogous to those seen in metazoans, where genetic diversification and incipient speciation caused by ecological factors have been reported in several genera.
Departments of Zoology and Statistics, University of Oxford, Peter Medawar Building, South Parks Road, Oxford OX1 3SY, UK.
