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

昆虫病原细菌黄杆菌的多基因系统发育分析。（肠杆菌科）及其线虫宿主微生物与其宿主在不同的生物学水平上相互作用。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-宿主协会导致的进化后果具有根本的重要性。昆虫病原细菌Xelihabdus spp.以及它们的线虫（蛔虫）宿主斯氏线虫属（Steinernema spp.）代表了陆地动物-微生物共生关系的一种新兴模式。黄杆菌属在斯氏线虫唯一的自由生活阶段，寄生在一个专门的寄生容器中。细菌-线虫对对多种昆虫具有致病性，并已成功地应用于世界各地的生物防治计划。PI Stock将研究共生细菌及其线虫宿主的进化历史，考虑多基因库。将比较Xobhabdus和Steinernema的遗传，以检验这两个合作伙伴的共同进化和多样化的假设。此外，涉及这种关联的生态，生理和形态特征的演变模式将进行检查。这项研究将产生第一个也是最完整的假设Xabhabdus-Steinernema进化亲和力。 此外，它将提供一个框架，记录和解释生态，生理和形态方面的这种伙伴关系。拟议研究的结果也将在共生和微生物生态学领域产生影响。例如，从这项研究中发展出来的共生性将为理解其他二元互惠协会的演变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.