Biological systems respond to stimuli in a context-dependent manner. These contexts can vary across different levels of biological organization, ranging from environmental differences to species interactions to genetic interactions. My dissertation research examines context-dependence and interaction across multiple scales in evolution and ecology, taking both experimental and theoretical approaches. I have focused on bacterial systems for my research, using the social bacterium Myxococcus xanthus as an experimental model system. In my research, I use an experimentally evolved lineage of M. xanthus to determine the extent that changing genetic backgrounds epistatically influence the expression of an allele involved in social surface motility. By re-introducing an allele of known phenotypic effect into genetic backgrounds across evolutionary time, and quantifying surface motility across evolutionary time points, I found a dynamic shift in the magnitude, and, eventually, the sign of the allelic effect on the swarming phenotype. Extending on this result, I have measured the how the epistatic effect is expressed across different abiotic environments and across different social life-history traits in M. xanthus. Further, I have investigated whether the epistatic interaction is consistent across parallel independent lineages that experienced the same selection pressures. Lastly, I theoretically investigated how spatial structure and kin recognition jointly influence the social evolution in rhizobium-legume mutualism. Together, these projects show how varying contexts – ranging from genetic to abiotic to social – can have profound impacts on ecological and evolutionary processes.
|Advisor:||Bever, James D., Velicer, Gregory J.|
|Commitee:||Lively, Curtis M., Wade, Michael J.|
|School Location:||United States -- Indiana|
|Source:||DAI-B 74/02(E), Dissertation Abstracts International|
|Subjects:||Biology, Ecology, Evolution and Development|
|Keywords:||Bacteria, Context-dependence, Ecology, Evolution, Interactions|
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