Wolbachia are the most widespread endosymbiotic bacteria in animals. In many arthropod host species, they manipulate reproduction via several mechanisms that favor their maternal transmission to offspring. Among them, cytoplasmic incompatibility (CI) promotes the spread of the symbiont by specifically decreasing the fertility of crosses involving infected males and uninfected females, via embryo mortality. These differences in reproductive efficiency may select for the avoidance of incompatible mating, a process called reinforcement, and thus contribute to population divergence. In the terrestrial isopod Porcellio dilatatus, the Wolbachia wPet strain infecting the subspecies P. d. petiti induces unidirectional CI with uninfected individuals of the subspecies P. d. dilatatus. To study the consequences of CI on P. d. dilatatus and P. d. petiti hybridization, mitochondrial haplotypes and Wolbachia infection dynamics, we used population cages seeded with different proportions of the 2 subspecies in which we monitored these genetic parameters 5 and 7 years after the initial setup. Analysis of microsatellite markers allowed evaluating the degree of hybridization between individuals of the 2 subspecies. These markers revealed an increase in P. d. dilatatus nuclear genetic signature in all mixed cages, reflecting an asymmetry in hybridization. Hybridization led to the introgressive acquisition of Wolbachia and mitochondrial haplotype from P. d. petiti into nuclear genomes dominated by alleles of P. d. dilatatus. We discuss these results with regards to Wolbachia effects on their host (CI and putative fitness cost), and to a possible reinforcement that may have led to assortative mating, as possible factors contributing to the observed results.

中文翻译：

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陆生等足类亚种间 Wolbachia 渐进获得的实验证据

Wolbachia是动物中最广泛的内共生细菌。在许多节肢动物宿主物种中，它们通过多种有利于母体向后代传播的机制来操纵繁殖。其中，细胞质不相容性 (CI) 通过胚胎死亡率专门降低涉及受感染雄性和未受感染雌性的杂交的生育力来促进共生体的传播。繁殖效率的这些差异可能会选择避免不相容的交配，这一过程称为强化，从而导致种群分化。在陆生等足动物Porcellio dilatatus 中，Wolbachia w Pet 菌株感染了P. d.亚种。小矮人诱导亚种 P.d. 未感染个体的单向 CI 。膨胀。研究 CI 对P. d. 的影响。dilatatus和P. d. petiti杂交、线粒体单倍型和沃尔巴克氏菌感染动力学，我们使用了以不同比例播种的 2 个亚种的种群笼，我们在初始设置后 5 年和 7 年监测了这些遗传参数。微卫星标记的分析允许评估两个亚种个体之间的杂交程度。这些标记显示P. d增加。所有混合笼中的dilatatus核遗传特征，反映了杂交的不对称性。杂交导致渐进式获得来自P. d. 的Wolbachia和线粒体单倍型。petiti进入由P. d.等位基因主导的核基因组。膨胀。我们讨论了Wolbachia对其宿主的影响（CI 和假定的适应度成本），以及可能导致分类交配的可能强化，这些结果可能是导致观察到的结果的因素。