Wang, Pu2024-02-092024-02-092021-12https://hdl.handle.net/11299/260682University of Minnesota Ph.D. dissertation. December 2021. Major: Ecology, Evolution and Behavior. Advisor: Michael Travisano. 1 computer file (PDF); vii, 127 pages + 1 supplementary .ZIP file.Eco-evolutionary feedbacks involve situations where environmental conditions influence evolutionary changes, which, in turn, feedback to the environment. Such interactions between ecological and evolutionary processes are prevalent in many biological systems from phage and bacteria to forests and animals. An increasing number of research projects address the significant impact of eco-evolutionary feedbacks in shaping the diversity of living organisms and their living niche, in many ecosystems in the modern world. Furthermore, interactions between ecology and evolution are taking place all the time. Thus, eco-evolutionary feedbacks would have significantly impacted the evolutionary history of life. The evolution of collective action also has significantly changed the form of life, by changing the way selection worked on organisms. Multicellularity, one example of the collective action of cells, is considered as one of the major transitions of life. The significance of such a major transition has been addressed more from promoting new organization or functions. However, the other, even more impactful, aspect of influencing the entire community via eco-evolutionary feedbacks has been less emphasized. Populations experiencing major transitions could alter the environments innovatively that would feedback on the subsequent evolutionary changes. In my thesis research, I addressed this impactful but less emphasized aspect of a major transition’s significance, by investigating the effect of eco-evolutionary feedbacks via collective actions. My projects demonstrated collective action is a scaffold for eco-evolutionary feedbacks from three perspectives. Firstly, I documented the evolutionary process of collective action. Then I created a predator-prey microcosm to describe how eco-evolutionary interactions occur along with the emergence of collective action. Lastly, I used genome sequencing techniques to investigate how eco-evolutionary interactions influence the entire communities including unevolved ones. I took the experimental evolution approach with different microbial systems to address each perspective. My research provided an empirical basis for investigating the important, yet less addressed aspect of the impact of major transitions. The effect of major transitions affected the evolving organism itself as well as the rest of the community by shaping the environment with new structures and functions. It also provides insights into the impact of eco-evolutionary feedbacks in the history of life.encollective actioneco-evolutionary feedbackecologyexperimental evolutionmicrobial commuintyThesis or Dissertation