Data from: Tetracycline-exposed Drosophila melanogaster males produce fewer offspring but a relative excess of sons

A large diversity of species possesses endosymbionts; these endosymbionts can exhibit mutualistic, parasitic, and commensal relationships with their hosts. Previous work has consistently revealed that depleting endosymbiont titer with antibiotic treatment can significantly alter host fitness and function, particularly with respect to reproductive phenotypes. Although these findings are often interpreted as resulting from the breakdown of highly coevolved symbioses, it is possible that antibiotic treatment itself rather than endosymbiont removal contributes to the observed perturbations in reproductive phenotypes. Here, we investigate the effect of tetracycline treatment on sex ratio and male reproductive fitness using Drosophila melanogaster as a model system. Our results indicate that tetracycline-treated males produce a relative excess of sons. We also find that tetracycline treatment reduces the number of progeny produced by treated males but not treated females. These findings are independent of the effects of tetracycline on Wolbachia titer and implicate the antibiotic itself as mediating these changes. It is yet unclear whether the sex ratio shift and reduction in male reproductive fitness are direct or indirect consequences of tetracycline exposure, and more work is needed to determine the molecular mechanisms by which these disturbances in reproductive phenotypes arise. Our data highlight the importance of considering the potentially confounding effects of antibiotic treatment when investigating the effects of endosymbiont depletion on host phenotypes.物种多样性丰富的类群均携带有内共生体 (endosymbiont)；此类内共生体可与其宿主建立互利共生、寄生及偏利共生的关联。既往研究均一致证实，通过抗生素处理降低内共生体滴度，可显著改变宿主的适合度与生理功能，尤以生殖表型的变化最为突出。尽管此类发现常被归因于高度共进化共生体系的瓦解，但也存在另一种可能：观测到的生殖表型扰动并非源于内共生体的清除，而是抗生素处理本身所导致。本研究以黑腹果蝇 (Drosophila melanogaster) 作为模式生物系统，探究四环素 (tetracycline) 处理对种群性比与雄性生殖适合度的影响。结果显示，经四环素处理的雄性果蝇所产生的子代中雄性个体占比偏高。此外我们还发现，四环素处理会降低处理组雄性果蝇的子代产出量，但对处理组雌性果蝇的子代数量无显著影响。上述研究结果与四环素对沃尔巴克氏体 (Wolbachia) 滴度的调控作用无关，提示抗生素本身介导了这些表型变化。目前仍无法明确，性比偏移与雄性生殖适合度降低究竟是四环素暴露的直接还是间接效应，后续仍需开展更多研究以阐明生殖表型出现此类扰动的分子机制。本研究数据凸显了在探究内共生体清除对宿主表型的影响时，需充分考虑抗生素处理本身可能带来的混淆效应，这一环节至关重要。