A multi-gene approach to assess phylogenetic relationships of the entomopathogenic bacteria Xenorhabdus spp. (Enterobacteriaceae) and their nematode hosts

应用多基因方法评价昆虫病原细菌Xnowhabdus spp.的系统发育关系(肠杆菌科)和它们的线虫宿主微生物和它们的宿主在不同的生物水平上相互作用。了解微生物如何在宿主之间移动，宿主和微生物如何相互适应，以及微生物与宿主之间的联系会带来什么进化后果，这是至关重要的。致虫性细菌Xnowhabdus spp.和它们的线虫(蛔虫)宿主--斯氏线虫。代表了一种新兴的陆地动物-微生物共生关系模型。致病杆菌Xnowhabdus spp.存在于斯氏线虫唯一自由生活阶段的特殊肠道容器中。这种细菌-线虫对对广泛的昆虫都是致病的，并已成功地在世界各地的生物防治计划中实施。皮斯托克将研究共生细菌及其线虫宿主的进化史，并考虑到多基因谱系。Xnowhabdus和Steinenema的系统发育将进行比较，以检验这两个合作伙伴的共同进化和多样化的假说。此外，还将研究这种关联所涉及的生态、生理和形态特征的进化模式。这项研究将产生第一个也是最完整的关于Xnowhabdus-Steinenema进化亲缘关系的假说。此外，它将为记录和解释这种伙伴关系的生态、生理和形态方面提供一个框架。拟议的研究结果还将对共生和微生物生态学领域产生影响。例如，这项研究开发的系统发生学将为理解其他二元互惠关系的进化和多样化建立一个框架。

A multi-gene approach to assess phylogenetic relationships of the entomopathogenic bacteria Xenorhabdus spp. (Enterobacteriaceae) and their nematode hostsMicrobes and their hosts interact with each other at different biological levels. Understanding how microbes move between hosts, how host and microbe adapt to each other, and what evolutionary consequences result from microbial-host associations is of fundamental importance. The insect-pathogenic bacteria Xenorhabdus spp. and their nematode (roundworms) hosts, Steinernema spp. represent an emerging model of terrestrial animal-microbe symbiotic relationships. Xenorhabdus spp. are harbored in a specialized intestinal-receptacle in the only free-living-stage of Steinernema nematodes. The bacterium-nematode pair is pathogenic for a wide range of insects and has successfully been implemented in biocontrol programs worldwide. PI Stock will study the evolutionary histories of both symbiotic-bacteria and their nematode-hosts considering a multigene repertoire. Xenorhabdus and Steinernema phylogenies will be compared to test the hypothesis of co-evolution and diversification of these two partners. Additionally, patterns of evolution of ecological, physiological and morphological traits involved in this association will be examined. This research will produce the first and most complete hypothesis of Xenorhabdus-Steinernema evolutionary affinities. Furthermore, it will provide a framework for documenting and interpreting ecological, physiological, and morphological aspects of this partnership. Results from the proposed research will also have implications in the fields of symbioses and microbial ecology. For example, the phylogenies developed from this research will set a framework for understanding the evolution and diversification of other binary mutualistic associations.