Research
Extant life depends on mutualistic microbial symbiosis - close physical associations between microorganisms and a host where both organisms benefit. Microbes provide an array of essential services to their hosts by augmenting nutrition, providing defense against parasites and pathogens, and increasing tolerance to abiotic stress. Nearly all organisms depend on microbes! The Stoy Lab focuses on developing an understanding of how these interactions evolve and persist. We are particularly interested in understanding the mechanisms underpinning generalized and species-rich interactions.
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....
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What mechanisms facilitate long-term cooperation in horizontally transmitted symbiotic mutualisms?
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How does generalist symbiosis evolve? How does generalist symbiosis persist?
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How do generalism and environmental transmission shape the evolution and adaptation of microbial symbionts?
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How do community-level dynamics alter pairwise evolutionary trajectories?
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Current Research Areas
Evolution and stability of environmentally acquired symbioses
Squash bugs and their symbionts
Environmentally acquired symbionts experience selection in both the external and host environment. This may result in tradeoffs for symbionts if adaptations for one environment are costly in another. The uncoupling of host and symbiont life cycles also increases opportunities for hosts to acquire exploitative symbionts. Using the interactions between the squash bug Anasa tristis and its bacterial Caballeronia symbionts, we are examining how the differential selection pressures experienced by symbionts alter their evolution and result in tradeoffs. We are exploring these ideas using molecular genomics and cross-infection studies.
Species-rich interactions and generalism
Coreid insects and their bacterial symbionts
Much of our understanding of coevolution between hosts and symbionts comes from empirical work and theory evaluating how specialized pairs of species reciprocally evolve in response to one another. However, the vast majority of mutualistic interactions are generalist or facultative. Highly specialized interactions are actually relatively rare. How these species-rich interactions maintain stability is not well understood. Using field-based analysis, genomics, and experimental tests, we are investigating how community-level dynamics alter pairwise evolutionary trajectories, symbiont adapation, and the maintenance of cooperation. We are examining these questions leveraging the generalist interactions between Caballeronia symbionts and three Coreid insect species.
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,
Generalism 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.
