Research
Mutualistic interactions between species are vital to life. Organisms across all domains of life depend on other species for an array of important functions, including supplementing nutrition, providing defense against pathogens, and increasing tolerance to environmental stressors. Our lab investigates the coevolutionary dynamics that underpin long-term persistence of these mutualistic interactions. Our approach uses evolutionary genetics, empirical manipulation, analysis of natural populations, and experimental evolution. Our empirical work is guided by the foundation established by theoretical models. We conduct this work using the naturally occurring interactions between Coreid insects and their bacterial symbionts and a model system of mutualistic crossfeeding Saccharomyces cerevisiae.
Stoy Lab Research Overview
Our lab aims to advance understanding of the evolutionary genetics and coevolutionary dynamics underlying mutualism stability. We use natural systems, including interactions between Coreid insects and bacterial Caballeronia symbionts. We also leverage experimental evolution and synthetic biology using Saccharomyces ceresivisae. Using this multi-faceted approach, we address oustanding questions in the field of mutualism, such as....
What mechanisms facilitate long-term cooperation in horizontally transmitted symbiotic mutualisms?
How does generalist symbiosis evolve? How does generalist symbiosis persist?
How do generalism and environmental transmission shape the evolution and adaptation of microbial symbionts?
How do community-level dynamics alter pairwise evolutionary trajectories?
How does vertical transmission evolve?
How does host behavior shape the evolution of symbiosis?
Some of Our Current Research Areas
(We have lots of projects ongoing! We are also eager to start new projects that prospective students find interesting!)
Horizontal symbiont transmission and the maintenance of cooperation
Coreidae insects and their symbionts
Insects in the family Coreidae depend on bacterial Caballeronia spp. symbionts. These insects require Caballeronia for both survival and development. The insects are required to acquire these symbionts from the environment rather than receiving symbionts from their parents. This should be costly! Hosts may acquire low quality symbionts from their environments, and selection on symbionts in the environment may favor traits for survival apart from hosts.
Our research uses field based surveys, behavior assays, and transmission experiments in semi-natural mesocosms to examing how cooperation persists in these associations despite the potential for these costs.
Species-rich interactions and generalism
Examining the temporal and spatial connectivity of symbiotic associations (Coreids and their symbionts)
Prior work testing patterns of Caballeronia specialization to their Coreid insect hosts has identified no obvious patterns of local adaptation (e.g. geographically structured specialization) or host-species specificity. Is this a generalist symbiosis? How and why does symbionts sharing amongst diverse hosts occur? How are these generalist symbioses stabilized?
We are currently leveraging metagenomics and network-based analysis to test for spatial and temporal structure across symbiont populations associated with closely related host species. Our genomics approach is complemented by lab-based analysis examining whether within-host symbiont strain variation and temporal changes to this strain variation alters insect fitness.
Symbiont-mediated pest management
Squash bugs and Caballeronia
Squash bugs are agricultural pests, causing mechanical damage to cucurbit crops and vectoring the pathogen Serratia ureilytica (formerly Serratia marcescens), which causes cucurbit yellow vine disease (CYVD). The symbiont Caballeronia competitively excludes Serratia from squash bug guts, reducing their vector competence. In our current work, we are characterizing strain-level variation and identifying symbiont loci required for insect association. This has the potential to inform the development of symbiont-mediated pest control strategies in agricultural settings.
Strategies to alleviate pest burden are critical for both traditional and organic farmers. Insects evolving resistance to insecticides is a constant struggle for traditional farmers, and organic farmers are often left essentially defenseless. Farmers regularly experience devastating crop loss due to insect pests, which are estimated to reduce annual world-wide crop yields by 20-40%, resulting in more than $220 billion in economic losses. The US government alone is expected to pay farmers $42.4 billion to cover crop losses in 2025. Our research is uniquely suited to contribute solutions to agricultural challenges resulting from pest burden,
.jpg)
Influence of Host Behavior on Symbiotic Evolution
Coreidae insects exhibit divergent behaviors that appear to undeprin symbiont transmission and acquisition. Our lab is examing the influence of host behavior in the evolution of insect-bacterial symbiosis using a combination of lab-based experiments, semi-natural mesocosms, and natural surveys.
Pairwise Coevolution, Diffuse Coevolution, and Mutualistic Benefits
Saccharomyces cerevisiae
Specialization is expected to facilitate the evolution of mutualistic benefits because partners exert consistent selection on one another for a specific resource or service. However, mutualism is most often generalist with species interacting with multiple partners across space or time. The consequences of this variation for the evolution of mutualistic benefits is not well understood. Leveraging a synthetic model system of mutualistical yeast obligately dependent on one another for amino acid cross-feeding and experimental evolution, we are assessing how partner fidelity alters the evolution of mutualistic benefits, resource production, and resource use efficiency.
