Data from: Tropical Drosophila pandora carry Wolbachia infections causing cytoplasmic incompatibility or male killing

Wolbachia infections have been described in several Drosophila species, but relatively few have been assessed for phenotypic effects. Cytoplasmic incompatibility (CI) is the most common phenotypic effect that has been detected, while some infections cause male killing or feminization, and many Wolbachia infections have few host effects. Here, we describe two new infections in a recently described species, Drosophila pandora, one of which causes near-complete CI and near-perfect maternal transmission (the “CI” strain). The other infection is a male killer (the “MK” strain), which we confirm by observing reinitiation of male production following tetracycline treatment. No incompatibility was detected in crosses between CI strain males and MK strain females, and rare MK males do not cause CI. Molecular analyses indicate that the CI and MK infections are distantly related and the CI infection is closely related to the wRi infection of Drosophila simulans. Two population surveys indicate that all individuals are infected with Wolbachia, but the MK infection is uncommon. Given patterns of incompatibility among the strains, the infection dynamics is expected to be governed by the relative fitness of the females, suggesting that the CI infection should have a higher fitness. This was evidenced by changes in infection frequencies and sex ratios in population cages initiated at different starting frequencies of the infections.

目前已有多项研究在多种果蝇属（Drosophila）物种中发现沃尔巴克氏体（Wolbachia）感染，但针对其表型效应的系统性评估相对匮乏。细胞质不相容（CI）是目前已检测到的最常见表型效应；部分沃尔巴克氏体感染会引发雄杀或雌性化，而多数感染对宿主几乎无明显表型影响。
本研究报道了新定名果蝇物种Drosophila pandora中的两株新型沃尔巴克氏体感染：其中一株可引发近乎完全的细胞质不相容（CI）表型，且母系传播效率接近完美，本研究将其命名为‘CI株’；另一株为雄杀型菌株（‘MK株’），我们通过四环素处理后雄性个体产生能力恢复的现象，证实了其雄杀特性。
CI株雄虫与MK株雌虫的杂交实验未检测到不相容现象，且罕见的MK株雄虫也无法引发CI。分子分析结果显示，CI株与MK株亲缘关系较远，而CI株与拟果蝇（Drosophila simulans）的wRi感染株系亲缘关系紧密。
两项种群抽样调查结果均显示，所有受试个体均携带沃尔巴克氏体，但MK株的感染频率较低。结合不同菌株间的不相容模式，推测该类感染的动态主要由雌虫的相对适合度决定，即CI株应具备更高的适合度。
这一推测通过以不同初始感染频率建立的种群笼中感染频率与性别比例的变化得到了验证。