The Department of Ecology and Evolutionary Biology is delighted to present the EEB First Paper Award to recognize Nia Johnson and Nikesh Dahal for their first lead-authored publications.
“Dicamba Drift Alters Plant–Herbivore Interactions at the Agro-Ecological Interface.” by Johnson, Nia M., and Baucom, Regina S.. 2022.
Natural populations evolve in response to biotic and abiotic changes in their environment, which shape species interactions and ecosystem dynamics. Agricultural systems can introduce novel conditions via herbicide exposure to non-crop habitats in surrounding fields. While herbicide drift is known to produce a variety of toxic effects in plants, little is known about its impact on nontarget wildlife species interactions. In a two-year study, we investigated the impact of herbicide drift on plant–herbivore interactions with common weed velvetleaf (Abutlion theophrasti) as the focal species. The findings reveal a significant increase in the phloem-feeding silverleaf whitefly (Bermisia tabaci) abundance on plants exposed to herbicide at drift rates of 0.5% and 1% of the field dose. We also identified a significant phenotypic trade-off between whitefly resistance and herbicide resistance in addition to whitefly resistance and relative growth rate in the presence of dicamba drift after increasing the populations grown in Year 2. In a follow-up greenhouse study, we found evidence that dicamba drift at 0.5% of the field dose significantly increased the average chlorophyll content (in milligrams per square centimeter) along with a positive correlation between whitefly abundance and chlorophyll content. Overall, these findings suggest herbicide exposure to nontarget communities can significantly alter herbivore populations, potentially impacting biodiversity and community dynamics of weed populations found at the agro-ecological interface.
"Impacts of an invasive filter-feeder on bacterial biodiversity are context dependent", by Nikesh Dahal, Paul Glyshaw, Glenn Carter, Henry A Vanderploeg, Vincent J Denef, FEMS Microbiology Ecology, 2022;, fiac149
Bacteria represent most of the biodiversity and play key roles in virtually every ecosystem. In doing so, bacteria act as part of complex communities shaped by interactions across all domains of life. Here, we report on direct interactions between bacteria and dreissenid mussels, a group of invasive filter-feeders threatening global aquatic systems due to high filtration rates. Previous studies showed that dreissenids can impact bacterial community structure by changing trait distributions and abundances of specific taxa. However, studies on bacterial community effects were conducted using water from Lake Michigan (an oligotrophic lake) only, and it is unknown whether similar patterns are observed in systems with differing nutrient regimes. We conducted ten short-term dreissenid grazing experiments in 2019 using water from two eutrophic lake regions—the western basin of Lake Erie and Saginaw Bay in Lake Huron. Predation by dreissenids led to decline in overall bacterial abundance and diversity in both lakes. However, feeding on bacteria was not observed during every experiment. We also found that traits related to feeding resistance are less phylogenetically conserved than previously thought. Our results highlight the role of temporal, spatial, and genomic heterogeneity in bacterial response dynamics to a globally important invasive filter feeder.
EEB encourages students to publish papers on their research during their career in the department. To acknowledge a student’s first, first-author publication as an EEB graduate student, the department will award a $30 Barnes and Noble gift card and a certificate of achievement to students who submit their first-author papers to the graduate program coordinator.