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

这个项目将研究物种的进化过程，这些物种生活在密切的联系中，彼此受益，共生。沃尔巴克氏体是一种细菌，通常与昆虫密切相关，它选择昆虫宿主的繁殖以确保自己的传播。沃尔巴克氏体的特定生活方式及其操纵昆虫的方式为（1）研究共生关系的进化和（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家庭和作物的常见害虫。然而，将沃尔巴克氏体从一个物种成功转移到新的目标昆虫物种已被证明是困难的，可能是因为沃尔巴克氏体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建一种昆虫物种的基因组变异，这种昆虫物种已经是与沃尔巴克氏体自然共生的一部分。随着时间的推移，昆虫和沃尔巴克氏体的变化将被跟踪，因为沃尔巴克氏体适应了宿主中新产生的遗传变异。除了为新的昆虫控制策略的发展提供信息外，阐明Wolbachia的适应过程可能有助于我们了解其他细菌-宿主相互作用。研究方法是通过制造一系列寄生蜂赤眼蜂的重组同雌品系，在宿主昆虫中产生遗传变异，随后跟踪Wolbachia在每个品系中的表现。与原始宿主相比，Wolbachia最初在重组宿主中表现不佳，但能够在短时间内适应新的昆虫。使用这个系统，沃尔巴克氏体和赤眼蜂pretiosum的变化可以用来识别基因和分子途径，是重要的共生体建立的早期阶段。基因组重测序方法将用于识别沃尔巴克氏体基因组中的突变。反过来，将使用RNA-Seq在早期和晚期时间点比较黄蜂的转录活性，以鉴定昆虫如何响应进化的共生体。该系统提供了一个研究共生体和宿主在共同进化过程中基因组、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.