Dissertation Research: From Parasitism to Mutualism: Effects of Wolbachia on Drosophila Survival and Reproduction

死去的寄生虫有时会变成仁慈的互助者。要了解可能影响这种转变的进化力量，需要一个既能找到寄生虫又能找到互助者的模型系统。大量文献记载了沃尔巴克氏菌对果蝇模拟物的寄生作用。然而，我们对模式生物黑腹果蝇的初步实验表明，一种有益的沃尔巴克氏菌菌株居住在该物种中。这种沃尔巴克氏菌的互惠形式可以延长黑腹果蝇的寿命高达35%。这项研究调查了这种延长的寿命是否会导致进化适应性的增强。为了做到这一点，研究人员将把受感染果蝇的特定年龄段的生存和繁殖与经过实验治疗以消除沃尔巴克氏菌感染的果蝇进行比较。实验将通过表征与沃尔巴克氏菌感染相关的一种新的表型-延长寿命，来提高对寄生虫-节肢动物共同进化的理解。这将可以量化沃尔巴克氏菌对果蝇健康的影响，并确定通常寄生的沃尔巴克氏菌是否正在成为果蝇宿主中的互助者。沃尔巴克氏菌-果蝇共生可能对研究寄生虫毒力的研究人员有用，并可能为测试关于从寄生到互惠共生的进化理论提供一个理想的系统。

Rand0104912Deadly parasites sometimes turn into benevolent mutualists. Understanding the evolutionary forces that can affect this transition requires a model system in which both parasites and mutualists are found. A large body of literature exists documenting the parasitic effects of Wolbachia in the fly Drosophila simulans. However, our preliminary experiments with the model organism Drosophila melanogaster indicate that a beneficial Wolbachia strain inhabits this species. This mutualistic form of Wolbachia can extend the lifespan of D. melanogaster flies up to 35%. This research investigates whether this increased lifespan leads to enhanced evolutionary fitness. To do this, the investigators will compare the age-specific survival and reproduction of infected flies with flies that have been experimentally treated with antibiotics to remove Wolbachia infection.The experiments will improve understanding of parasite-arthropod coevolution by characterizing a novel phenotype, extended lifespan, associated with Wolbachia infection. This will allow quantification of Wolbachia's effect on Drosophila fitness and determine if normally parasitic Wolbachia are becoming mutualists in Drosophila hosts. The Wolbachia-Drosophila symbiosis may prove useful to researchers investigating the virulence of parasites, and may provide an ideal system for testing evolutionary theories about the transition from parasitism to mutualism.