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.

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，但针对其表型效应开展系统性评估的案例相对较少。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性致死或雌性化，而多数感染对宿主几乎无显著影响。本研究报道了一种新近被描述的果蝇物种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），且母系传递效率接近完美，我们将其命名为“CI菌株”；另一株为雄性致死菌株（“MK菌株”），并通过观察四环素处理后雄性个体产生恢复的现象，验证了该表型。CI菌株雄虫与MK菌株雌虫的杂交实验未检测到不相容现象，且罕见的MK雄虫也不会引发细胞质不相容。分子分析结果显示，CI菌株与MK菌株亲缘关系较远，而CI菌株与拟果蝇（Drosophila simulans）的wRi菌株亲缘关系紧密。两项种群普查结果均表明，该物种所有个体均携带沃尔巴克氏体，但MK菌株的感染率较低。结合不同菌株间的不相配模式，其感染动态预计由雌虫的相对适合度调控，推测CI菌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构建的种群笼中感染频率与性比的动态变化得到了验证。