My research focuses on understanding how human-mediated (anthropogenic) stressors affect the ecology and evolution of species interactions. I have investigated these questions in the context of plant–plant, plant–pollinator, and plant–microbe interactions. I have also frequently used agrochemical pollution caused by herbicide drift as a model for anthropogenic stress. Herbicide drift is a major issue in agriculture that occurs when herbicide particles move away from application sites through the air, and it is often caused by top synthetic auxin herbicides (e.g. 2,4-D and dicamba). Even though the concentration of herbicide that ultimately reaches non-target organisms via drift can be as low as ~1% of the field application rate, my prior work has shown that herbicide drift can still have significant ecological consequences. In the future, I aim to expand the scope of my research program to investigate other pertinent stressors such as urbanization, drought, heat, and multiple stressors to further advance our knowledge about the nature of these crucial ecological relationships and how to maintain them in our modern world.
Current Projects
What is the role of the legume root microbiome in sustaining ecosystem services under herbicide stress?
A growing body of research is showing that the root microbiome is an important driver of plant health. For example, microbes living within root tissues or in the rhizosphere can biosynthesize natural compounds that promote plant growth or detoxify harmful compounds like heavy metals and pesticides in the surrounding soil. However, in light of recent agricultural intensification, understanding whether the root microbiome influences plant tolerance to herbicide drift remains a pertinent question. In particular, it is unclear whether the composition of the root microbiome interacts with herbicide exposures to affect plant resilience or the ability of plants to maintain critical root mutualisms, such as those with nitrogen-fixing rhizobial bacteria or arbuscular mycorrhizal fungi (AMF). My current USDA-funded postdoctoral research project with the Baucom and James labs at the University of Michigan is addressing these questions using a combination of field observational studies, greenhouse experiments, bioinformatic analyses, and agriculturally-relevant legumes (red clover, white clover, and soybean) as model plant species. Ultimately, we seek to uncover the genetic mechanisms underpinning how root-associated microbes mediate plant productivity and ecosystem services under herbicide stress, and thereby gain insight into how the root microbiome could potentially be manipulated to maximize beneficial ecological outcomes in agroecosystems.
Are changes in plant–pollinator interactions caused by herbicide stress mediated by changes in floral chemistry?
For the majority of the world’s flowering plants, reproduction relies on the ability to attract and interact with insect pollinators. In response to this selective pressure, plants have evolved a suite of floral traits that have long fascinated evolutionary ecologists. Previously, my research team and I found that herbicide drift caused by dicamba can disrupt plant-pollinator interactions by reducing pollinator visitation to several plant species commonly found in agroecosystems (Baucom, Iriart, et al. 2025). However, we do not currently know if these disruptions are the result of herbicide-mediated changes in floral traits, such as the quality or quantity of pollen and nectar rewards. In collaboration with an interdisciplinary team of chemists, agroecologists, and computational biologists at the University of Michigan, I am addressing this knowledge gap by analyzing data from a 2025 field experiment where we evaluated floral rewards and plant-pollinator networks in herbicide-exposed and non-exposed multi-species plant communities. This project is supported by U-M’s Meet the Moment Research Initiative called PHACTS: Pollinator Health: Assess, Construct, Test, and Survey.
Previous Projects
Will herbicide drift cost plants their mutualisms with N-fixing rhizobial bacteria?
Plant mutualistic interactions with soil bacteria called rhizobia provide the key ecosystem service of biological nitrogen fixation. In these interactions, rhizobia transform atmospheric nitrogen into a bioavailable form that plants can absorb in exchange for carbon, which ultimately enhances soil fertility and contributes to terrestrial nutrient cycling. However, herbicide drift is a modern anthropogenic force that plants and their rhizobial partners are commonly exposed to and are likely evolving in response to. In order to understand the consequences of herbicide drift, particularly from the widely-used herbicide dicamba, on the evolutionary ecology of the plant-rhizobia mutualism, my research team and I conducted greenhouse and growth chamber experiments with the red clover study system. Overall, we uncovered that stress caused by herbicide drift often had detrimental effects on the quantity and quality of plant-rhizobia interactions as demonstrated by symbiotic root nodule formation and biological nitrogen fixation. However, genetic variation from rhizobial partners was an especially important driver of mutualism outcomes, more so even than plant genetic variation (Iriart et al., 2024, Iriart et al., 2026).
Will herbicide drift cause shifts in plant community structure?
Plant communities that border agricultural fields provide essential resources for wildlife, especially floral resources for pollinators. If plant species vary in tolerance to herbicide drift, then this could result in plant community shifts favoring more tolerant species. Consequently, this interspecific variation could compromise floral resource availability in agroecosystems. In a greenhouse study (Iriart et al., 2022), my research team and I confirmed that there was interspecific variation in tolerance to dicamba drift across 25 plant species common to agroecosystems. While some species were negatively impacted, others were unaffected or showed overcompensatory responses. Drift also caused salient differences in co-flowering interactions within synthetic plant communities. Drift reduced the degree and intensity of flowering overlap among species and shifted species roles (from dominant to inferior floral producers) according to species’ drift tolerance. In a follow-up study (Iriart et al., 2026), my team and I exposed nine agro-eco plant species to dicamba drift and examined tolerance across three different field environments in Michigan, Pennsylvania, and Tennessee. We found further support that drift tolerance is species-dependent, but also found new evidence that it can also be context-dependent. In particular, we observed more interspecific variation in tolerance in Michigan, a result that was partially explained by patterns of insect herbivory. Through structural equation modeling, we also identified potential functional pathways underlying dicamba drift tolerance across plant species.
Research in Action!
