Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
Department of Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Wien, Austria.
J Evol Biol. 2022 Jun;35(6):788-802. doi: 10.1111/jeb.14016. Epub 2022 May 9.
Wolbachia bacteria are common endosymbionts of many arthropods found in gonads and various somatic tissues. They manipulate host reproduction to enhance their transmission and confer complex effects on fitness-related traits. Some of these effects can serve to increase the survival and transmission efficiency of Wolbachia in the host population. The Wolbachia-Drosophila melanogaster system represents a powerful model to study the evolutionary dynamics of host-microbe interactions and infections. Over the past decades, there has been a replacement of the ancestral wMelCS Wolbachia variant by the more recent wMel variant in worldwide D. melanogaster populations, but the reasons remain unknown. To investigate how environmental change and genetic variation of the symbiont affect host developmental and adult life-history traits, we compared effects of both Wolbachia variants and uninfected controls in wild-caught D. melanogaster strains at three developmental temperatures. While Wolbachia did not influence any developmental life-history traits, we found that both lifespan and fecundity of host females were increased without apparent fitness trade-offs. Interestingly, wMelCS-infected flies were more fecund than uninfected and wMel-infected flies. By contrast, males infected with wMel died sooner, indicating sex-specific effects of infection that are specific to the Wolbachia variant. Our study uncovered complex temperature-specific effects of Wolbachia infections, which suggests that symbiont-host interactions in nature are strongly dependent on the genotypes of both partners and the thermal environment.
沃尔巴克氏体细菌是常见的内共生体，存在于许多节肢动物的性腺和各种体组织中。它们操纵宿主的繁殖，以增强自身的传播，并对与适应性相关的特征产生复杂的影响。其中一些影响可以提高沃尔巴克氏体在宿主种群中的生存和传播效率。沃尔巴克氏体-黑腹果蝇系统是研究宿主-微生物相互作用和感染的进化动态的有力模型。在过去的几十年里，世界范围内的黑腹果蝇种群中，由祖先的 wMelCS 沃尔巴克氏体变体被最近的 wMel 变体所取代，但原因仍不清楚。为了研究环境变化和共生体的遗传变异如何影响宿主的发育和成年生活史特征，我们比较了在三个发育温度下，两种沃尔巴克氏体变体和未感染对照对野生捕获的黑腹果蝇品系的影响。虽然沃尔巴克氏体没有影响任何发育生活史特征，但我们发现宿主雌性的寿命和繁殖力都增加了，而没有明显的适应性权衡。有趣的是，感染了 wMelCS 的果蝇比未感染和感染了 wMel 的果蝇繁殖力更强。相比之下，感染了 wMel 的雄性果蝇死亡得更早，这表明感染具有特定于沃尔巴克氏体变体的性别特异性效应。我们的研究揭示了沃尔巴克氏体感染的复杂的特定于温度的效应，这表明自然中共生体-宿主的相互作用强烈依赖于两个伙伴的基因型和热环境。
