Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede-Boqer campus, 84990, Midreshet Ben-Gurion, Israel.
Wyler Department of Dryland Agriculture, French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede-Boqer campus, 84990, Midreshet Ben-Gurion, Israel.
FEMS Microbiol Ecol. 2018 Oct 1;94(10). doi: 10.1093/femsec/fiy157.
Endosymbionts-microbes that live within and engage in prolonged and intimate associations with their hosts-are gaining recognition for their direct impact on plant and animal reproduction. Here we used the overlooked Wolbachia-flea system to explore the possibility that endosymbionts may also play a role as mediators in shaping the reproductive success of their hosts. We simultaneously quantified the Wolbachia density in field- and laboratory-originated fleas that fed and mated on rodents for either 5 or 10 days and assessed their body size and current reproductive success. By combining multigroup analysis and model selection approaches, we teased apart the contribution of the direct effects of the flea's physiological age and body size and the mediation effect of its Wolbachia endosymbionts on flea reproductive success, and we showed that the latter was stronger than the former. However, interestingly, the mediation effect was manifested only in laboratory-originated fleas, for which the increase in Wolbachia with age translated into lower reproductive success. These results suggest that some well-supported phenomena, such as aging effects, may be driven by endosymbionts and show once again that the role of endosymbionts in shaping the reproductive success of their host depends on their selective environment.
内共生体——生活在其宿主体内并与之进行长期而密切的共生的微生物——因其对植物和动物繁殖的直接影响而受到越来越多的关注。在这里，我们利用被忽视的沃尔巴克氏体-跳蚤系统来探索内共生体是否也可能作为宿主生殖成功的中介发挥作用。我们同时量化了在野外和实验室环境中饲养并与啮齿动物交配 5 天或 10 天的跳蚤中的沃尔巴克氏体密度，并评估了它们的体型大小和当前的生殖成功。通过结合多组分析和模型选择方法，我们区分了跳蚤的生理年龄和体型的直接影响以及其沃尔巴克氏体内共生体对跳蚤生殖成功的中介作用的贡献，并表明后者比前者更强。然而，有趣的是，这种中介作用仅在实验室起源的跳蚤中表现出来，因为随着年龄的增长，沃尔巴克氏体的增加导致生殖成功率降低。这些结果表明，一些被广泛支持的现象，如衰老效应，可能是由内共生体驱动的，并再次表明内共生体在塑造宿主生殖成功中的作用取决于它们的选择环境。
