Research

Some Current Projects in the Lab

The projects summarized here are all collaborations with the lab of Grieg Steward, viral and microbial ecologist extraordinaire.

Explaining the niches of mixotrophic and autotrophic phytoplankton

A large fraction of ocean primary production is performed by small eukaryotic phytoplankton from a bewildering diversity of clades. Many of these taxa are thought to be mixotrophs that both photosynthesize and prey upon bacteria, but the functional diversity among these groups and the drivers of their community structure are poorly understood. We have been using a large collection of novel isolates to characterize tradeoffs between phototrophic and phagotrophic performance, and test whether trophic strategy explains niche differences along major environmental gradients. We have also been developing ecological theory for how trophic strategies in plankton communities emerge from physiological tradeoffs and principles of resource compeition.

Making sense of virus size

Viruses vary immensely in size, with the largest ʻgiantʻ viruses having genomes a thousandfold larger and virions a millionfold larger than the smallest viruses. Phytoplankton and other single-celled protists are infected by viruses from across this size spectrum, but we donʻt know why such a diverse spectrum of sizes exist, and how the fitness of different sizes varies across environments. We are performing experiments with diverse novel isolates, and developing quantitative models, to start making sense of virus size.

Costs and mechanisms of resistance to viral infection

Infection by viruses can cause their hosts to evolve mechanisms of resistance, but this resistance likely comes at a cost. The cost of resistance is a fundamental quantity for ecology and evolution, because it will affect coevolutionary dynamics, the relative abundance of susceptible and resistant genotypes, population mortality rates, the coexistence of competing species, and ecosystem productivity. In a project funded by NSF EPSCoR we are studying costs of resistance in the eukaryotic phytoplankton Micromonas, how resistance affects different competitive traits, and the genomic basis of resistance adaptations.