Baldo Laura, Ayoub Nadia A, Hayashi Cheryl Y, Russell Jacob A, Stahlhut Julie K, Werren John H
Department of Biology, University of California, 900 University Avenue, Riverside, CA 92521, USA.
Mol Ecol. 2008 Jan;17(2):557-69. doi: 10.1111/j.1365-294X.2007.03608.x. Epub 2007 Dec 20.
The pandemic distribution of Wolbachia (alpha-proteobacteria) across arthropods is largely due to the ability of these maternally inherited endosymbionts to successfully shift hosts across species boundaries. Yet it remains unclear whether Wolbachia has preferential routes of transfer among species. Here, we examined populations of eight species of the North American funnel-web spider genus Agelenopsis to evaluate whether Wolbachia show evidence for host specificity and the relative contribution of horizontal vs. vertical transmission of strains within and among related host species. Wolbachia strains were characterized by multilocus sequence typing (MLST) and Wolbachia surface protein (WSP) sequences, and analysed in relation to host phylogeny, mitochondrial diversity and geographical range. Results indicate that at least three sets of divergent Wolbachia strains invaded the genus Agelenopsis. After each invasion, the Wolbachia strains preferentially shuffled across species of this host genus by horizontal transfer rather than cospeciation. Decoupling of Wolbachia and host mitochondrial haplotype (mitotypes) evolutionary histories within single species reveals an extensive contribution of horizontal transfer also in the rapid dispersal of Wolbachia among conspecific host populations. These findings provide some of the strongest evidence to support the association of related Wolbachia strains with related hosts by means of both vertical and horizontal strain transmission. Similar analyses across a broader range of invertebrate taxa are needed, using sensitive methods for strain typing such as MLST, to determine if this pattern of Wolbachia dispersal is peculiar to Agelenopsis (or spiders), or is in fact a general pattern in arthropods.
沃尔巴克氏体（α-变形菌）在节肢动物中的广泛分布很大程度上归因于这些母系遗传的内共生体能够成功跨越物种界限转移宿主。然而，尚不清楚沃尔巴克氏体在物种间是否有优先的传播途径。在这里，我们研究了北美漏斗网蜘蛛属Agelenopsis的八个物种的种群，以评估沃尔巴克氏体是否表现出宿主特异性的证据，以及菌株在相关宿主物种内部和之间水平传播与垂直传播的相对贡献。通过多位点序列分型（MLST）和沃尔巴克氏体表面蛋白（WSP）序列对沃尔巴克氏体菌株进行了表征，并结合宿主系统发育、线粒体多样性和地理范围进行了分析。结果表明，至少有三组不同的沃尔巴克氏体菌株侵入了Agelenopsis属。每次入侵后，沃尔巴克氏体菌株通过水平转移而非共同物种形成优先在该宿主属的物种间重新组合。单一物种内沃尔巴克氏体和宿主线粒体单倍型（线粒体类型）进化历史的解耦也揭示了水平转移在沃尔巴克氏体在同种宿主种群中快速传播中的广泛贡献。这些发现提供了一些最有力的证据，以支持相关的沃尔巴克氏体菌株通过垂直和水平菌株传播与相关宿主的关联。需要使用MLST等敏感的菌株分型方法，在更广泛的无脊椎动物类群中进行类似分析，以确定这种沃尔巴克氏体传播模式是Agelenopsis（或蜘蛛）特有的，还是实际上是节肢动物中的普遍模式。
