CAREER: Host-Parasite Coevolutionary Dynamics: Testing key hypotheses in host mating system evolution

职业：宿主-寄生虫协同进化动力学：测试宿主交配系统进化的关键假设

• 批准号: 1750553
• 负责人: Levi Morran
• 金额: $ 85.24万
• 依托单位: Emory University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-15 至 2024-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1750553&HistoricalAwards=false
• 关键词: CAREER; Host; Parasite; Coevolutionary; Dynamics

Reproduction is the most essential biological process. It influences how DNA is inherited from one generation to the next. Organisms actually have many different ways of reproducing. It is unclear why the most common should involve genetic contributions from two parents (bi-parental reproduction) as opposed to one (uni-parental reproduction). One important consequence of bi-parental reproduction is that it produces more genetically variable offspring. Why this is an advantage, however, is unclear. One possibility is that genetically variable offspring are more likely to escape infection from parasites and diseases that have adapted to the parents' genetic make-up. Another is that the genetic variability is helpful more generally for adaptation to changing environments. This project uses the nematode worm Caenorhabditis elegans, which can reproduce either uni- or bi-parentally, along with its bacterial parasite, Serratia marcescens, to experimentally test these ideas. The project will also contribute to teaching and training students at many levels, providing opportunities for them to learn scientific methods in a hands-on fashion. It will integrate research with education in undergraduate teaching labs and will include developing and implementing new teaching laboratory classes. It will also train graduate students. Finally, it will include an outreach program that will bring hypothesis testing science to a neighborhood with many young children from underrepresented groups in science. The questions of both how and why bi-parental reproduction is maintained in nature largely remain a mystery in evolutionary biology. Currently, the Red Queen hypothesis (RQH) is the most well supported hypothesis regarding the evolution and maintenance of outcrossing. The central prediction of the RQH is that negative frequency-dependent selection, imposed by coevolving parasites, favors reproduction via outcrossing over self-fertilization in host populations. Although a rapidly growing number of studies demonstrate the ability of coevolving parasites to favor host outcrossing over host self-fertilization, the mode of selection imposed by coevolving parasites, and in general, the coevolutionary dynamics between outcrossing hosts and their respective parasites remain unclear. Here, the fundamental predictions of the RQH will be comprehensively tested in perhaps the only experimental system currently capable of permitting such a test. Specifically, the host, Caenorhabditis elegans, and parasite, Serratia marcescens, populations will be experimentally evolved to determine if coevolving parasites are necessary for the evolution and maintenance of outcrossing, or if only a dynamic changing environment is required. After which, the phenotypic and underlying genetic changes in the hosts and parasites, as well as the mode (or modes) of selection that result from antagonistic coevolution, will be determined through a combination of phenotypic assays, next-generation sequencing, functional genetic testing via transformation, and subsequent experimental evolution.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.

生殖是最基本的生物过程。 它影响DNA如何从一代遗传到下一代。生物体实际上有许多不同的繁殖方式。 目前还不清楚为什么最常见的应该涉及遗传贡献的两个父母（双亲生殖），而不是一个（单亲生殖）。双亲繁殖的一个重要后果是它产生了更多的遗传变异后代。 然而，为什么这是一个优势还不清楚。 一种可能性是，遗传变异的后代更有可能逃避适应父母遗传组成的寄生虫和疾病的感染。另一个是遗传变异性更普遍地有助于适应不断变化的环境。这个项目使用线虫秀丽隐杆线虫，它可以单亲或双亲繁殖，沿着它的细菌寄生虫粘质沙雷氏菌，以实验测试这些想法。 该项目还将有助于多层次学生的教学和培训，为他们提供以实践方式学习科学方法的机会。它将在本科教学实验室中将研究与教育相结合，并将包括开发和实施新的教学实验室课程。它还将培养研究生。最后，它将包括一个外展计划，将假设检验科学带到一个社区，那里有许多来自科学代表性不足群体的幼儿。在进化生物学中，双亲繁殖是如何以及为什么在自然界中得以维持的问题在很大程度上仍然是一个谜。目前，红皇后假说（RQH）是关于异交的进化和维持的最受支持的假说。RQH的中心预测是，负频率依赖性选择，共同进化的寄生虫，有利于繁殖通过异交超过自花受精在宿主种群。虽然越来越多的研究表明，共同进化的寄生虫，有利于主机异交的主机自受精的能力，模式的选择施加共同进化的寄生虫，并在一般情况下，异交主机和各自的寄生虫之间的共同进化动力学仍然不清楚。在这里，RQH的基本预测将在可能是目前唯一能够允许这种测试的实验系统中进行全面测试。具体而言，主机，秀丽隐杆线虫，和寄生虫，粘质沙雷氏菌，人口将实验进化，以确定是否共同进化的寄生虫是必要的进化和维持的异交，或者如果只需要一个动态变化的环境。在此之后，宿主和寄生虫的表型和潜在的遗传变化，以及模式由拮抗性共同进化产生的选择（或模式），将通过表型测定、下一代测序、通过转化的功能性遗传测试，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的学术价值和更广泛的影响审查标准。

项目成果

Host Defense Mechanisms Induce Genome Instability Leading to Rapid Evolution in an Opportunistic Fungal Pathogen

• DOI: 10.1128/iai.00328-21
• 发表时间: 2021-12
• 期刊: Infection and Immunity
• 影响因子: 3.1
• 作者: Amanda C. Smith;Levi T. Morran;Meleah A. Hickman

Advantages of laboratory natural selection in the applied sciences

实验室自然选择在应用科学中的优势

• DOI: 10.1111/jeb.13964
• 发表时间: 2021
• 期刊: Journal of Evolutionary Biology
• 影响因子: 2.1
• 作者: Lewis, Jordan A.;Morran, Levi T.
• 通讯作者: Morran, Levi T.

Host heterogeneity mitigates virulence evolution

• DOI: 10.1098/rsbl.2019.0744
• 发表时间: 2020-01-29
• 期刊: BIOLOGY LETTERS
• 影响因子: 3.3
• 作者: White, P. Signe;Choi, Angela;Morran, Levi
• 通讯作者: Morran, Levi

Antagonistic Coevolution Limits the Range of Host Defense in C. elegans Populations

• DOI: 10.3389/fcimb.2022.758745
• 发表时间: 2022-02-17
• 期刊: FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY
• 影响因子: 5.7
• 作者: Lewis，Jordan A.;Penley，McKenna J.;Morran，Levi T.
• 通讯作者: Morran，Levi T.

The evolution of parasite host range in heterogeneous host populations

• DOI: 10.1111/jeb.13608
• 发表时间: 2020-02
• 期刊: Journal of Evolutionary Biology
• 影响因子: 2.1
• 作者: A. Gibson;Helena Baffoe-Bonnie;McKenna J. Penley;Julie Lin;Raythe Owens;Arooj Khalid;Levi T. Morran