Data from: Multiple endosymbiont infections and reproductive manipulations in a linyphiid spider population

In many arthropods, maternally inherited endosymbiotic bacteria can increase infection frequency by manipulating host reproduction. Multiple infections of different bacteria in a single host population are common, yet few studies have documented concurrent endosymbiont phenotypes or explored their potential interactions. We hypothesized that spiders might be a particularly useful taxon for investigating endosymbiont interactions, because they are host to a plethora of endosymbiotic bacteria and frequently exhibit multiple infections. We established two matrilines from the same population of the linyphiid spider Mermessus fradeorum and then used antibiotic curing and controlled mating assays to demonstrate that each matriline was subject to a distinct endosymbiotic reproductive manipulation. One matriline was co-infected with Rickettsia and Wolbachia and produced offspring with a radical female bias. Antibiotic treatment eliminated both endosymbionts and restored an even sex ratio to subsequent generations. Chromosomal and fecundity observations suggest a feminization mechanism. In the other matriline, a separate factorial mating assay of cured and infected spiders demonstrated strong cytoplasmic incompatibility (CI) induced by a different strain of Wolbachia. However, males with this Wolbachia induced only mild CI when mated with the Rickettsia–Wolbachia females. In a subsequent survey of a field population of M. fradeorum, we detected these same three endosymbionts infecting 55% of the spiders in almost all possible combinations, with nearly half of the infected spiders exhibiting multiple infection. Our results suggest that a dynamic network of endosymbionts may interact both within multiply infected hosts and within a population subject to multiple strong reproductive manipulations.

在诸多节肢动物中，母系遗传的内共生细菌可通过操控宿主生殖提升自身感染频率。单一宿主种群内同时感染多种不同细菌的现象十分普遍，但目前鲜有研究同时记录内共生体的表型，或探究它们之间的潜在相互作用。
我们提出假说：蜘蛛或许是研究内共生体相互作用的理想类群，因为其宿主携带有大量内共生细菌，且常出现多重感染。我们从同一皿蛛科蜘蛛*Mermessus fradeorum*种群中建立了两个母系谱系，随后通过抗生素清除法与控制性交配实验证实，每个母系谱系均受到独特的内共生体生殖操控。
其中一个母系谱系同时感染立克次体（Rickettsia）与沃尔巴克氏体（Wolbachia），其后代呈现极端的雌性偏倚。抗生素处理可清除这两种内共生体，并使后续子代恢复至均等性比。染色体观察与繁殖力数据提示其作用机制为雌性化。
在另一母系谱系中，我们对清除感染与未清除感染的蜘蛛开展析因交配实验，结果显示该种群内的沃尔巴克氏体（Wolbachia）不同菌株可诱导强烈的细胞质不相容性（cytoplasmic incompatibility, CI）。然而，当携带该沃尔巴克氏体的雄蛛与感染立克次体-沃尔巴克氏体的雌蛛交配时，仅会引发轻度的细胞质不相容。
后续对*Mermessus fradeorum*野外种群的调查显示，上述三种内共生体的感染率达55%，几乎所有可能的感染组合均被检测到，近半数受感染蜘蛛呈现多重感染状态。
我们的研究结果表明，内共生体或构成一个动态网络，可在多重感染的宿主体内以及经历多种强生殖操控的种群中发生相互作用。