Date on Master's Thesis/Doctoral Dissertation

5-2023

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biology

Degree Program

Biology, PhD

Committee Chair

Emery, Sarah

Committee Co-Chair (if applicable)

Christian, Natalie

Committee Member

Christian, Natalie

Committee Member

Fuselier, Linda

Committee Member

Perlin, Michael

Committee Member

Rua, Megan

Author's Keywords

global change; fungal endophytes; dunes; succession; nitrogen deposition; social learning

Abstract

Global change is a crucial process, affecting every organism, from the billions of humans on earth, to the billions of microbes in the soil belowground. Evaluating the impacts of the many drastic changes associated with global change is essential in advancing our understanding in how to mitigate these consequences. Alongside the production of basic ecological knowledge associated with these environmental changes, improving education practices to promote science literacy surrounding global change is another step towards a more optimistic future. This dissertation investigates global change from two standpoints: ecologically, where increased atmospheric nitrogen (N) deposition alters plant-fungal endophyte symbiosis, and pedagogically, using the pressing issue of global change to evaluate best practices for student learning. The dissertation has been divided into five chapters. Chapter one serves as an introduction, building a foundation for this work. Chapter two examines the direct and interactive effects of microbial symbiosis and N addition on plant community succession. As part of a long-term experiment in Lake Michigan dunes where nitrogen was added at 3 different levels, I evaluated effects of the vertically transmitted fungal endophyte, Epichloë amarillans, in Ammophila breviligulata, a dominant ecosystem-engineering dune grass species. I found that nitrogen addition decreased the diversity of colonizing plants, but only when the endophyte was present within Ammophila. Nitrogen addition directly modified plant community composition through increased colonization by C4 grasses. Chapter three took these ideas further by evaluating the influence of N deposition and the aboveground vertically transmitted Epichloë symbiont on the belowground fungal root endophyte community. Epichlöe presence increased root endophyte species richness by 17% overall in host plants, but only shifted root endophyte community composition in nitrogen-enriched conditions. The fourth chapter used a pedagogical perspective to understand how students within an environmental biology course at the University of Louisville best learn about global change. Using both qualitative and quantitative measurements, I assessed the influence of virtual versus traditional learning environments on student engagement with discussions. Findings suggest a need for educators to implement intentional blended approaches to discussions, as online boards encourage engaged writing which promoted individual critical thinking, while in-person discussions aided in social learning from peers and motivation in the classroom. The final chapter summarizes my findings and discusses future directions of my work. These studies contribute positively to forwarding various approaches to the climate crisis through research of ecological principles and pedagogic tools to increase science literacy among students. This dissertation is unique in that it addresses both ecological and human responses to global change.

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