A novel approach to parasite population genetics: Experimental infection reveals geographic differentiation, recombination and host-mediated population structure in Pasteuria ramosa, a bacterial parasite of Daphnia
A novel approach to parasite population genetics: Experimental infection reveals geographic differentiation, recombination and host-mediated population structure in Pasteuria ramosa, a bacterial parasite of Daphnia
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DOI：
10.1111/mec.12159
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发表时间：
2013-02-01
影响因子：
4.9
通讯作者：
Ebert, D.
中科院分区：
文献类型：
--
作者：
Andras, J. P.;Ebert, D.
寄生虫的种群结构对宿主-寄生虫系统的生态学和进化至关重要。在这里，我们调查的群体遗传学的多枝巴氏杆菌，水蚤的细菌寄生虫。我们使用天然的多枝原蜱孢子银行从两个地理上分开的池塘沉积物实验感染大型蚤宿主克隆的抗性表型是以前已知的面板。通过这种方式，我们能够根据地理位置、寄主抗性表型和寄主基因型来评估多枝侧耳的种群结构。总的来说，多枝假单胞菌的遗传多样性较高，几乎所有的假单胞菌都感染了D.麦格纳主持一个以上的寄生虫单倍型。基于对重组单倍型和相对低水平的连锁不平衡的观察，我们得出结论，P. ramosa从事实质性重组。隔离强烈分化池，表明基因流是空间限制。根据寄主的抗性表型，在一个池塘中分离出了分枝巴氏杆菌分离株，据我们所知，这一结果以前没有报道过非人寄生虫。为了评估实验感染与天然多枝假单胞菌分离株的可比性，我们检查了自然感染的D.原产于两个池塘之一的麦格纳。我们发现，来自同一来源池塘的相同宿主抗性表型的实验感染和自然感染是无法区分的，这表明实验感染提供了一种代表性采样多枝假单胞菌多样性的手段，同时减少了通常与寄生虫流行病研究相关的采样偏差。这些结果扩展了我们对这种模式寄生虫的了解，为现有的大量研究提供了重要的背景，并将指导未来宿主-寄生虫系统研究的设计。
The population structure of parasites is central to the ecology and evolution of host-parasite systems. Here, we investigate the population genetics of Pasteuria ramosa, a bacterial parasite of Daphnia. We used natural P. ramosa spore banks from the sediments of two geographically well-separated ponds to experimentally infect a panel of Daphnia magna host clones whose resistance phenotypes were previously known. In this way, we were able to assess the population structure of P. ramosa based on geography, host resistance phenotype and host genotype. Overall, genetic diversity of P. ramosa was high, and nearly all infected D. magna hosted more than one parasite haplotype. On the basis of the observation of recombinant haplotypes and relatively low levels of linkage disequilibrium, we conclude that P. ramosa engages in substantial recombination. Isolates were strongly differentiated by pond, indicating that gene flow is spatially restricted. Pasteuria ramosa isolates within one pond were segregated completely based on the resistance phenotype of the hosta result that, to our knowledge, has not been previously reported for a nonhuman parasite. To assess the comparability of experimental infections with natural P. ramosa isolates, we examined the population structure of naturally infected D. magna native to one of the two source ponds. We found that experimental and natural infections of the same host resistance phenotype from the same source pond were indistinguishable, indicating that experimental infections provide a means to representatively sample the diversity of P. ramosa while reducing the sampling bias often associated with studies of parasite epidemics. These results expand our knowledge of this model parasite, provide important context for the large existing body of research on this system and will guide the design of future studies of this host-parasite system.