Super-generalist predation in a model microbe Dictyostelium discoideum

这个项目将研究生物是如何进化成通才或专才的捕食者的，它使用的是一种以细菌为猎物的变形虫——盘基骨虫。这种变形虫可以吃掉许多不同种类的细菌，尽管它们有各种各样的防御系统。该项目将试图确定变形虫是否认为所有可食用细菌都是相同的，或者它们必须以不同的方式处理不同的细菌。对于它们以不同方式处理的细菌，它将询问变形虫的策略变化是否有效。这项工作将确定变形虫基因在处理猎物方面的重要作用，并将验证这些基因进化得特别快的观点，因为它们必须对不断变化的细菌策略做出反应。由于细菌可以引起疾病，为我们的微生物群提供服务，并对农业和营养循环产生影响，因此需要更好地了解它们的捕食者。这项研究将包括对来自不同背景的本科生、研究生和博士后学者的培训。项目团队将通过公开演讲和流行文章、弗格森农贸市场的摊位、博客、针对大学课堂的计算机项目以及针对高中生的行为和进化日，与不同群体分享他们的知识。研究人员将利用一组15种不同细菌来调查盘状棘球绦虫处理不同猎物的不同程度。本文将通过四种研究方法来探索这一系列的猎物：变形虫在不同猎物之间转换的代价，变形虫对不同猎物的实验进化的反应，变形虫在不同猎物上的转录组变化，以及变形虫基因敲除文库的选择。这四项研究中的每一项都将通过类似的多元统计和聚类方法进行分析，给出四种独立的观点，即哪些猎物的处理方式相似。研究人员将进一步以两种方式使用转录组学和基因敲除选择的结果。首先，基因敲除选择结果——基因敲除是增加还是减少阿米巴原虫对每个猎物的适应性——将用于测试不同猎物的转录变化的适应性有多广。其次，那些在这个意义上表现出最强烈适应性变化的基因将定义一组“捕食基因”，这些基因将被测试，以确定捕食是否会推动进化军备竞赛。该项目由综合有机体系统部的行为系统项目共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project will study how organisms evolve to be either generalist or specialist predators using an amoeba, Dictyostelium discoideum, that preys on bacteria. This amoeba can eat many different bacterial species, despite their wide variety of defenses. The project will seek to determine whether the amoebas see all edible bacteria as equivalent, or the degree to which they must handle different bacteria in different ways. For bacteria that they do handle in different ways, it will ask whether the amoeba’s changes in strategy are effective. This work will determine amoeba genes that important in handling prey and will test the idea that these genes evolve particularly rapidly because they must respond to changing bacterial strategies. Since bacteria can cause disease, provide services in our microbiomes, and have impacts on agriculture and nutrient cycling, a better understand their predators is needed. The study will involve the training of undergraduates from diverse backgrounds, along with graduate students and a post-doctoral scholar. The project team will reach out to share its knowledge with diverse groups via public talks and popular articles, a booth at the Ferguson Farmer’s market, a blog, and a computer project for university classes, and a Behavior and Evolution Day for high school students. The researchers will investigate the extent to which D. discoideum handles distinct prey differently using a panel of 15 diverse bacteria species. This array of prey species will be explored by four methods: studies of costs to amoebas of switching between prey species, responses to experimental evolution of amoebas on different prey, amoeba transcriptomic changes on different prey, and selection of amoeba gene knockout libraries on different prey. Each of these four studies will be analyzed by similar multivariate statistical and clustering methods, giving four independent takes on which prey species are handled similarly. The researchers will use the results of the transcriptomics and the knockout selections in two further ways. First, the knockout selection results – do gene knockouts increase or decrease amoeba fitness on each prey – will be used to test how broadly adaptive the transcriptional changes on different prey are. Second, those genes that most strongly show adaptive changes in this sense will define a set of “predation genes” which will be tested to see if predation drives evolutionary arms races.This project is co-funded by the Behavioral Systems program in the Division of Integrative Organismal Systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.