CAREER: Integrating microbiology and population genetics through experimentation with the origins of a microbial mutualism

这项研究将研究两种互利微生物的进化。长期以来，人类一直被似乎互相帮助的物种所吸引，例如传粉者和开花植物之间的相互作用，或者我们的身体和栖息在它们身上的微生物之间的相互作用。由于这些物种影响彼此的繁荣能力，我们希望看到物种间的进化协调，因为每个物种都适应了另一个物种的变化。有些突变只有在共同进化的伙伴存在的情况下才是有益的。然而，我们不知道这些相互变化发生的频率，因为我们经常无法观察到它们发生的情况，而且在许多物种中，很难确定哪些变化是对伙伴物种的反应，哪些是对环境其他特征的适应。这项研究将通过观察这些相互作用在微生物系统中的演变来回答这些问题。这项研究还将导致开发一个关于微生物进化的主动学习模块，用于普通本科生微生物学课程，并为本科生开发两门探究式课程。在这些课程中，本科生将测试在进化过程中发生的突变对种群在有或没有互利共生的情况下蓬勃发展的能力的影响，使他们能够以综合的方式学习进化和微生物生态学和遗传学的基本概念。 该实验将包括两个物种的细菌脱硫弧菌普通Hildenborough和古菌甲烷球菌maripaludis社区，沿着与单一物种的控制人口。复制社区将经过3000代的进化。这种共同进化互惠共生的群体遗传学将通过在几个时间间隔内对每个物种的基因组进行测序来确定。将通过比较种群与过去和未来的互利主义者的适应性，通过将感兴趣的突变转移到祖先品系中，以及通过重建沿着世系主线的所有中间体并测试它们在有和没有互利主义者伙伴的情况下的适应性，来确定种群对生物环境的适应程度。

This research will study the evolution of two mutually-beneficial microorganisms. Humankind has long been captivated by species that seem to help each other out, such as interactions between pollinators and flowering plants or our bodies and the microorganisms that inhabit them. Because such species affect each other's ability to flourish, we expect to see some coordination of evolution across species as each adapts to the changes imposed by the other. Some mutations should only be beneficial in the presence of the coevolving partner. However, we do not know how often these reciprocal changes occur because we often cannot observe them as they happen and in many species it is difficult to determine which changes were a response to a partner species and which were adaptations to other features of their environment. This research will answer these questions by observing these interactions evolve in a microbial system. The research will also result in the development of an active-learning module on microbial evolution to be used in general undergraduate microbiology courses and the development of two inquiry-based courses for undergraduates. In these courses undergraduates will test the effects of mutations that occurred during evolution on the ability of populations to flourish with or without mutualism, allowing them to learn fundamental concepts of evolution and microbial ecology and genetics in an integrated manner. The experiment will consist of a two-species community of the bacteria Desulfovibrio vulgaris Hildenborough and the archaeon Methanococcus maripaludis, along with single-species control populations. Replicate communities will evolve over 3000 generations. The population genetics of this coevoling mutualism will be determined by sequencing the genomes of each species at several time intervals. The level of adaptation of populations to the biotic environment will be determined by comparing the fitness of populations with past and future mutualists, by moving mutations of interest into ancestoral strains, and by reconstructing all intermediates along the main line of descent and testing their fitness with and without a mutualist partner.