Multiscale microbial systems ecology and evolution /

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Bibliographic Details
Author / Creator:Gibbons, Sean Michael, author.
Ann Arbor : ProQuest Dissertations & Theses, 2015
Description:1 electronic resource (120 pages)
Format: E-Resource Dissertations
Local Note:School code: 0330
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Other authors / contributors:University of Chicago. degree granting institution.
Notes:Advisors: Jack A. Gilbert; Maureen L. Coleman Committee members: Maureen L. Coleman; Jack A. Gilbert; Rick L. Stevens; Jacob R. Waldbauer.
Dissertation Abstracts International, Volume: 77-02(E), Section: B.
Summary:Microorganisms are the forbears of all life on Earth and form the foundation of all ecosystems, past and present. Microbial metabolism is essential for maintaining homeostasis of the atmosphere and oceans and for preserving the health and well-being of multicellular organisms. Microbial ecology has lagged behind classical ecology because of our historical inability to directly observe these complex, invisible communities with any degree of precision. However, over the past decade, high-throughput molecular techniques (sequencing and mass-spectrometry) have cracked open this microbial cosmos and made quantitative microbial systems ecology possible. In many ways, microbial communities are fundamentally different from macro-ecological systems, with vastly higher dispersal rates, shorter generation times, rapid evolution (on ecologically-relevant timescales), high frequencies of lateral gene transfer and enormous metabolic diversity. Despite these differences, we have found that traditional ecological theories can often be applied successfully to microbial systems. In a brief span of time, microbial ecology has moved from natural history to a more fundamental science, thanks to an established body of theory, the tools and techniques of molecular biology and bioinformatics, and the experimental tractability of microbes. Microbial ecology is positioned to make fundamental contributions to the fields of ecology and evolution in the coming years, as standardized methods allow for multiscale assessments of microbial diversity in the field, and as microbial ecosystems are brought into the laboratory for controlled experimentation.
In the following dissertation, I review recent advances in the field and present a selection of my own work that explores microbial diversity at vastly different scales. At the planetary scale, I investigate how microbial diversity is shaped and maintained across hundreds ecosystems and provide evidence for a global `seed bank' of rare microbes. At the single-community scale, I investigate how microbial diversity is shaped by environmental perturbations in controlled microcosm studies, and suggest resolutions to current controversies in the diversity-disturbance literature. Finally, at the single population level, I look at how gene expression shapes gene nucleotide content distributions in streamlined genomes, and what this reveals about bacterial genome evolution. Together, these studies show how microbial communities can be investigated at many different spatial and temporal scales, both in situ and in the laboratory, to shed light on the complex interplay between biotic diversity, environmental stability, ecosystem function, ecological interactions, and evolutionary processes.