DISSERTATION RESEARCH: Evolutionary strategies for adaptation in Wolbachia, a reproductive symbiont of arthropods.

这个项目将研究生活在紧密联系和互惠互利的物种共生的进化过程。沃尔巴克氏菌是一种细菌，通常与昆虫密切相关，它利用昆虫宿主的繁殖来确保自己的传播。沃尔巴克氏菌特殊的生活方式及其操纵昆虫的方式，为(1)研究共生进化和(2)开发控制昆虫种群的替代方法提供了独特的机会，包括传播疾病的蚊子和常见的家庭和农作物害虫。然而，事实证明，成功地将沃尔巴克氏菌从一个物种转移到新的目标昆虫物种是困难的，可能是因为沃尔巴克氏菌不适应新的昆虫物种，因为它们没有共同进化。该研究项目将使用一种新的系统来创造一种昆虫物种的基因组变异，这种变异已经是与沃尔巴克氏菌自然共生的一部分。随着沃尔巴克氏菌适应宿主中新产生的遗传变异，随着时间的推移，昆虫和沃尔巴克氏菌的变化都将被跟踪。除了为新的昆虫控制策略的发展提供信息外，阐明沃尔巴克氏菌的适应过程可能有助于我们了解其他细菌与宿主的相互作用。研究方法是通过建立一系列寄生黄蜂的等雌重组品系来创造寄主昆虫的遗传变异，并随后跟踪沃尔巴克氏菌在每个品系中的表现。与原始寄主相比，沃尔巴克氏菌最初在重组寄主中的表现较差，但能够在短时间内适应新的昆虫。利用这个系统，沃尔巴克氏菌和赤眼蜂的变化都可以用来识别在共生体建立的早期阶段重要的基因和分子途径。将使用基因组重新测序的方法来识别沃尔巴克氏菌基因组中的突变。反过来，将使用RNA-Seq比较黄蜂在早期和晚期的转录活性，以确定昆虫如何对进化中的共生体做出反应。该系统提供了一个研究共生体和寄主在共同进化过程中的基因组、生理和表型变化的平台。

This project will study the process of evolution of species that live in close association and benefit each other, symbioses. Wolbachia is a bacterium, commonly found in close associations with insects, that co-opts the reproduction of an insect host to ensure its own transmission. The specific lifestyle of Wolbachia, and the ways in which it manipulates insects, provide a unique opportunity to (1) study the evolution of symbiosis, and (2) develop alternative methods for controlling insect populations including disease transmitting mosquitoes and common pests of homes and crops. However, the successful transfer of Wolbachia from one species to new target insect species has proven difficult, likely because Wolbachia is not adapted to the new species of insect since they have not coevolved. The research project will use a novel system to create variation in the genome of an insect species that is already part of a natural symbiosis with Wolbachia. Changes in both the insect and Wolbachia will then be tracked over time, as Wolbachia adapts to the newly created genetic variation present in its host. Beyond informing the development of novel insect control strategies, elucidating the adaptive process in Wolbachia may help us understand other bacteria-host interactions.The research approach is to create genetic variation in a host insect by making a series of recombinant isofemale lines of the parasitic wasp, Trichogramma pretiosum, and subsequently to track the performance of Wolbachia in each of those lines. Compared to the original host, Wolbachia performs poorly in the recombinant hosts initially, but is able to adapt to the new insects in a short time span. Using this system, changes to both Wolbachia and Trichogramma pretiosum can be used to identify genes and molecular pathways that are important in the early stages of symbiont establishment. A genome re-sequencing approach will be used to identify mutations in the Wolbachia genome. Reciprocally, transcriptional activity of the wasps will be compared at early and late time points using RNA-Seq, so as to identify how the insect responds to the evolving symbiont. This system provides a platform with which to study changes to the genomes, physiology, and phenotypes of symbionts and hosts during co-evolution.