DISSERTATION RESEARCH: Determining the impact of symbiont metabolic role in symbiont genome decay in Adelgidae (Hemiptera)

这项研究将测试共生体基因组大小变化是基于宿主饮食以及共生关系的年龄的假设。以植物汁液为食的昆虫与细菌形成密切的伙伴关系或共生关系。这些伙伴关系允许昆虫通过补充饮食来以营养贫乏的植物汁液为食。这种联系对双方都有好处，并带来了后果。结果之一是细菌通常进化成具有极小的基因组。在许多昆虫群体中，这些细菌伙伴关系在数百万年内保持稳定。这项研究将测试细菌的基因组大小是否取决于昆虫和细菌共同进化的时间，或者是否需要涉及宿主饮食类型的更复杂的解释。 这项研究将拓宽我们对自然界中细菌-昆虫关系的一般理解，这一主题可能会影响农业和自然保护。 此外，该项目还包括努力鼓励美洲原住民学生通过为他们提供实践实验室经验来追求科学教育。以前的研究表明，共生细菌的基因组极度减少，关键营养供应途径的功能丧失。虽然最近的研究已经开始研究共生体中基因组降解的模式和克里思的细节，但重要的问题仍然存在。选择在驱动较小的基因组大小方面有多重要？共生体的年龄有多重要？共生体的特定代谢或生态作用是否影响基因组大小的变化？虽然取得了一些进展，但由于这些因素难以理清，研究受到了限制。这项研究引入了一种新的系统，该系统消除了几个混杂因素，以便更清楚地了解是什么导致共生体中基因组大小减少。共生体的基因组将比较密切相关的谱系的阿耳特里德昆虫，共享一个共同的共生体，但不同的营养可通过主机饮食。这将允许宿主饮食营养成分的影响进行检查，同时控制共生的年龄。一些共生体的基因组从内部和跨adelgid谱系也将测序的原因共生体基因组衰退的更普遍的调查。将量化所有核心代谢类别中的基因缺失，特别是营养供应。然后将分析基因组衰变的模式，以检测衰变与年龄的关联、营养作用和其他因素之间的相关性。

This research will test the assumption that symbiont genome size variation is based on host diet as well as on the age of the symbiotic relationship. Plant-sap feeding insects form close partnerships, or symbioses, with bacteria. These partnerships allow the insects to feed on nutrient-poor plant-sap by supplementing their diets. This association is beneficial for both partners and it comes with consequences. One consequence is that the bacteria typically evolve to have extremely small genomes. In many groups of insects these bacterial partnerships are stable over millions of years. This study will test if the genome size of a bacteria is determined by how long the insect and bacteria have coevolved, or if it requires a more complicated explanation involving the host's diet type. The study will broaden our general understanding of bacterial-insect associations in nature, a topic that may impact agriculture and conservation. Additionally, this project includes efforts to encourage Native American students to pursue education in the sciences by providing them with hands-on laboratory experiences.Previous studies have revealed the extreme reductions in the genomes of symbiotic bacteria and the loss of functions in critical nutrient-provisioning pathways. While recent studies have begun to examine the details of mode and tempo of genome degradation in symbionts, important questions remain. How important is selection in driving smaller genome size? How important is the age of the symbiotic associations? Do the particular metabolic or ecological roles of the symbionts influence the change in genome size? Progress has been made, but studies have been constrained by the fact that these factors are hard to disentangle. This research introduces a novel system that removes several confounding factors to allow a clearer view of what causes decreased genome size in symbionts. The genomes of symbionts will be compared in closely related lineages of adelgid insects that share a common symbiont but differ in the nutrients available through host diet. This will allow the influence of host diet nutrient content to be examined while controlling for the age of the symbiosis. A number of symbiont genomes from within and across adelgid lineages will also be sequenced for a more general survey of the causes of symbiont genome decay. Gene deletions in all core metabolic categories, particularly nutritional provisioning will be quantified. Patterns of genome decay will then be analyzed to detect correlation between decay and age of the association, nutritional role and other factors.