Nature is rarely predictable. Fluctuations in the flux of energy in an environment limit the opportunities for the growth, survival, and reproduction of individuals. Despite these constraints, microorganisms are found in virtually every known energy-limited environment on the plant. This dissertation primarily focuses on examining the evolutionary and ecological consequences of these energetic fluctuations on microorganisms. First, I examine the population dynamics and evolutionary outcomes of a phylogenetically diverse set of microbial taxa. I present evidence that the recycling of dead cells (i.e., necromass) by the few that survive drives an increase in the net rate of growth over time in energy-limited environments. Next, the evolutionary consequences of reduced rates of metabolic activity (i.e., dormancy) are examined and synthesized through a combination of novel simulations and a review of the existing literature. I then examine approaches for quantifying the degree of genetic parallelism in microbial experimental evolution, a prerequisite for the final chapter. Finally, in the last chapter the predicted consequences are tested using a long-term evolution experiment, where I examine the effect of dormancy on the rate and direction of molecular evolutionary dynamics. I find that the ability to enter a dormant state reduces the level of genetic diversity and alters the trajectory of mutations, but does not affect the direction of evolution. The work presented in this dissertation indicates that energy-limitation places a severe constraint on the ecological and evolutionary dynamics of microbial populations.
|Advisor:||Lennon, Jay T.|
|Commitee:||Hahn, Matthew W., Fukuyama, Julia A., Lively, Curt M.|
|School Location:||United States -- Indiana|
|Source:||DAI-B 82/1(E), Dissertation Abstracts International|
|Subjects:||Evolution and Development, Ecology, Microbiology|
|Keywords:||Bacillus, Dormancy, Experimental evolution, Microbial ecology, Seed banks, Seedbanks|
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