Collaborative Research: Evolutionary Dynamics of Endosymbiont-Borne Adaptation in Aphids

[9527635]莫兰蚜虫和许多其他植食昆虫依赖于一种叫做内共生菌的特殊细菌，这种细菌生活在细胞内，并由昆虫母亲传给后代。在蚜虫内的内共生体的最好的记录功能是提供必需的营养物质，色氨酸。因为蚜虫在它们的饮食中不摄取色氨酸，它们依靠它们的内共生体来提供这种营养。因此，产生色氨酸的细菌基因对昆虫宿主的生长和繁殖至关重要。本研究探讨了蚜虫中色氨酸产生的内共生基因的进化。先前的研究表明，这些基因在某些蚜虫种类的内共生体中显示出一种不寻常的加速进化模式。这个项目使用分子生物学的方法来检验这种基因进化速率变化的解释。由于内共生体是许多作物害虫的重要组成部分，包括蚜虫、粉虱和蚧虫等群体，因此本研究将有助于了解基础知识，最终导致害虫管理方面的进展。农业昆虫学家认为，影响昆虫生产性能的内共生性状的短期进化对害虫新品种的起源具有重要意义。这项研究将是第一个直接研究对昆虫生存和繁殖至关重要的内共生基因进化的研究之一。

9527635 MORAN Aphids and many other plant-feeding insects are dependent on specialized bacteria, called endosymbionts, that live within cells and that are transmitted from the mother insect to her offspring. The best documented function of endosymbionts within aphids is the provision of the essential nutrient, tryptophan. Because aphids do not ingest tryptophan in their diets, they depend on their endosymbionts to provide this nutrient. Thus the bacterial genes that underlie tryptophan production are critical to the growth and reproduction of the insect host. This study examines the evolution of the endosymbiont genes underlying tryptophan production in aphids. Previous work has indicated that these genes show an unusual pattern of accelerated evolution in the endosymbionts of certain aphid species. This project uses methods of molecular biology to test explanations for the variation in evolutionary rates in this gene. Because endosymbionts are an essential component of many crop pests, including such groups as aphids, whiteflies, and scale insects, this study will contribute to fundamental knowledge that could ultimately lead to progress in pest management. Agricultural entomologists have suggested that the short-term evolution of endosymbiont traits that affect insect performance is important in the origin of new strains of pest species. This study will be one of the first to directly examine evolution within endosymbiont genes that are critical to insect survival and reproduction.