Current projects
Our current research is focused on exploring the responses of environmental bacteria and phages to abiotic factors, primarily the effects of temperature on marine phage-host interactions. To do this, we are working with individual strains (using a seasonal strain library from the Long Island Sound, which will be expanded to include coastal South Carolina isolates), as well as studying whole communities.
With our work, we aim to:
(1) improve predictions of the effects of environmental change on microbial populations and communities
(2) understand how context-dependent phage dynamics impact animal and human disease risk
(3) leverage non-model systems to expand our basic understanding of diverse host-virus interactions
Characterizing spatial and temporal variation in microbial traits
Predicting how organisms might be impacted by future thermal change requires an understanding of their current responses to temperature. For microbes, we know relatively little about how variation in temperature responses is distributed across space and time, and the genetic basis of this variation. For this project, we are measuring the temperature-dependence of various phenotypes in bacteria and phages from our marine strain library. In particular, we are interested in how GxGxE interactions shape host and phage traits, with a specific interest in the effects of prophages on host responses to temperature. We are expanding on prior work showing that prophage activity can explain intraspecific variation in thermal performance, driving an overall reduction in performance and shaping adaptation to high temperature.
Mechanisms and consequences of adaptation to abiotic stress
Microbes in the environment frequently experience stress from changes in abiotic factors. This is particularly true for marine microbes that find themselves in tide pools, which can shift relatively rapidly in factors like temperature and salinity. Some may even experience desiccation (like microbes in the pictured tide pool). Using experimental evolution, we are testing how marine bacteria and phages adapt to stressors like temperature and desiccation, and the consequences this can have for other traits.
Viral adaptation to temperature on a global scale
To expand beyond the microbes of Long Island Sound, we are also studying genes that may be associated with adaptation to temperature in publicly available viral metagenomics data. We are using various tools for purposes such as viral annotation, host prediction, and protein structural prediction to explore whether certain virus-encoded genes may be important for microbial survival in extreme climatic conditions.
Prior projects
Evolution of phage resistance in vitro and in planta
Bacteria often rapidly evolve resistance to phages in the lab, but does this happen in more ecologically-relevant contexts? We found that for the plant pathogen P. syringae, resistance evolution is greatly reduced when interacting on plants due to context-dependence in the relative fitness of resistant mutants.
Seedling assay for phage effectiveness on tomato
Experiments with plants in growth chambers can be challenging due to space and time limitations. Seedling-based assays are an efficient option for researchers interested in characterizing plant-associated bacteria-phage interactions. We found that phage-mediated reduction of pathogen densities and disease symptoms can be rapidly assessed on tomato seedlings.
Effects of host coevolution on phage evolution
Fitness of a virus genotype depends on the hosts that are available for infection. In this project, we tested how allowing or preventing bacterial coevolution shapes phage genotypic and phenotypic evolution. Coevolution led to more mutations, host range expansion, and a more predictable genotype-phenotype relationship.