Rooting microbes in plant adaptation: The evolution of locally adaptive plant-microbe interactions

While an organism’s phenotype can partially be attributed to heritable genetic variation, recent work has highlighted that phenotype is also partially influenced by an organism’s interactions with its associated microbial symbionts. Indeed, all eukaryotic organisms are seemingly colonized by diverse communities of microorganisms that can frequently alter their host’s phenotype through their various activities. However, while a number of microbial taxa that are important drivers of host phenotype have been identified, these interactions are often cryptic, with spatially and temporally variable effects on their hosts. This dissertation attempts to disentangle these interactions by examining drivers of both the host’s and their microbial partners’ evolution, specifically focusing on how their interactions may evolve to generate locally adaptive host phenotypes, using the interactions between plants and their root-associated microbes as a model symbiosis. I investigated multiple agents that may select on either the plant host or microbial partners, including the abiotic environment, as well as the reciprocal selection from each partner on the other. Overall, I found that these plant-microbe interactions could quickly evolve to provide locally adaptive benefits to the plants, though the drivers of this local adaptation varied. In one study I found plants were locally adapted to their historic environment only when provided with microbial partners, suggesting that these microbes were necessary for the evolution of the locally adaptive plant traits, with plants potentially evolving to adaptively interact with these microbes in their home environment. Additionally, across two experiments I found that plant-associated microbes had rapidly evolved to benefit plants in their current environment. In one of these, I found that plants were a strong selective agent on their microbes, driving the evolution of microbes that provided a locally adaptive benefit. In the other, I again found these microbes evolved to provide a locally adaptive benefit to the plant, however, the plant was unnecessary in driving the evolution of these locally adaptive microbes. These results suggested that while microbes can explicitly evolve traits to benefit their hosts, these beneficial traits can sometimes simply be a byproduct of these microbes’ own adaptation to their environment. Overall, this dissertation illustrates that host-microbe interactions are dynamic, with the potential to rapidly evolve in response to novel environments.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ecol, Evol, Conservation Biol

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Ricks, Kevin Daniel

Contributors dc:contributor

• O'Dwyer, James P
• Yannarell , Anthony C
• Heath, Katy D
• Kent, Angela D

• Ecology
• Evolution
• Symbioses
• Byproducts
• Local Adaptation
• Plant-microbe Interactions

Statement dc:rights

• Copyright 2023 Kevin Ricks

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/121425

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F121425