Evolution of Parasite Specialization Across an Ancient Agricultural System

所有的寄生虫都是专家。这种专业化是因为寄生虫需要有效地接触和感染至少一些宿主，这通常是以能够感染其他宿主为代价的。在大范围内，寄生虫物种适应一组特定的宿主物种。在更细微的范围内，许多寄生虫菌株专门克服一个物种内有限范围的宿主基因型的防御。对于宿主和寄生虫在细微尺度上的适应进化过程如何与更广泛尺度上的寄生虫宿主范围的进化联系在一起，人们几乎不了解，部分原因是很少有宿主-寄生虫系统能够同时在这两个尺度上进行研究。在这个项目中，研究人员将利用一个自然的、古老的宿主-寄生虫系统，该系统允许在多个尺度上对寄生虫专门化进行分子研究。Ecovopsis是一种寄生真菌的多样性属，它攻击由种植真菌的蚂蚁种植的其他真菌。不同的Ecovopsis种能够侵染不同种类的栽培真菌，在较细的尺度上，不同的Ecovopsis基因型能够感染和利用不同的寄主基因型。这种寄生虫的特异性表明了一种动态的适应模式，并提供了一个难得的机会来在多个尺度上识别寄生虫专门化的潜在特征。作为该项目的一部分，本科生的班级将通过调查寄生虫的寄主范围和寄生虫的基因组来学习寄生虫的进化，中学生将通过综合科学和艺术的方法学习寄生虫的进化。在现有关于Ecovopsis多样性和寄主范围的知识以及最近对Ecovopsis基因组的洞察的基础上，研究人员将结合寄生虫-宿主相互作用、转录组学、种群基因组学和遗传操作的实验分析，以探索病原体专门化的遗传基础。具体地说，研究人员将利用转录学和功能分析来确定寄生虫对它们可以感染和不能感染的宿主菌株的反应背后的基因。他们将通过跨物种和跨物种菌株的基因组比较，根据寄生虫基因组其余部分的进化来研究这些基因的进化。综上所述，研究人员将能够评估类似的特征是否在一个易驯化的古老宿主-寄生虫系统中以广泛和精细的进化规模构成寄生虫专门化的基础。这一奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

All parasites are specialists. This specialization is driven by the need for parasites to efficiently encounter and infect at least some hosts, which often comes at the cost of being able to infect others. At a broad-scale, parasite species adapt to a particular set of host species. At a finer-scale, many parasite strains specialize at overcoming the defenses of a narrow range of host genotypes within a species. There is little understanding of how evolutionary processes of host and parasite adaptation at the fine scale are linked to the evolution of parasite host ranges at broader scales, in part because few host-parasite systems are amenable to research at both scales. In this project the researchers will capitalize on a natural, ancient host-parasite system that allows for molecular investigation of parasite specialization at multiple scales. Escovopsis is a diverse genus of parasitic fungus that attacks other fungi cultivated by fungus-growing ants. Different Escovopsis species are able to infect different species of cultivated fungi, and at a finer scale, different Escovopsis genotypes are able to infect and utilize different host genotypes. Such parasite specificity suggests a dynamic pattern of adaptation and provides a rare opportunity to identify traits underlying parasite specialization at multiple scales. As part of this project, classes of undergraduate students will study parasite evolution through investigation of the parasites' host ranges and the parasites' genomes, and middle school students will learn about parasite evolution through an integrated science and art approach. Building on existing knowledge of Escovopsis diversity and host range, as well as recently gained insights into the Escovopsis genome, the researchers will couple experimental assays of parasite-host interactions, transcriptomics, population genomics and genetic manipulation to explore the genetic underpinnings of pathogen specialization. Specifically, the researchers will utilize transcriptomics and functional assays to identify the gene underlying the parasites' responses to host strains that they can and cannot infect. They will study the evolution of these genes in light of the evolution of the rest of the parasite genome through genomic comparisons across species and across strains within species. Taken together, the researchers will be able to assess whether similar traits underlie parasite specialization at broad and fine evolutionary scales in a tractable, ancient host-parasite system.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.