Agraulis vanillae caterpillar.  Photo: Edward Rooks, via Wikimedia Commons, CC BY-SA 4.0

Our research focuses broadly on how variation contributes to population and community ecology, and how interspecific interactions affect ecological and evolutionary processes at larger scales. Our work uses both field experiments and mathematical/computing tools to extrapolate interactions such as host-pathogen interactions and mutualism to larger contexts such as population and community dynamics and evolutionary change.

See below for some current and prior projects.

Disease ecology

Ecological causes and consequences of variation in an insect-baculovirus interaction

Our current empirical work focuses on the Agraulis vanillae-NPV system, with the goal of understanding how diverse sources of intraspecific variation affect the population dynamics of host-pathogen interactions, including pathogen genetic variation, host variation, and environmental variation due to anthropogenic factors of urbanization and climate change. We use a combination of field and lab experiments to measure key pathogen life history traits such as continuous variation in transmission, and use these empirical data to fit.  Our field work is primarily conducted in urban areas in San Diego, CA and in gradients from urban to natural environments in Puerto Rico. Equitable and inclusive fieldwork in collaboration with local communities is a key goal of this work: if you are interested in collaborating, are looking for a postdoctoral position or summer Research Experience for Undergraduates, or just think you’ve seen these caterpillars and want more info, we would love to hear from you!   Contact us here.

This project was funded by an NSF CAREER grant in 2022.

Individual and population-level effects of water in a tritrophic system:
impacts on pollination, herbivory, and parasitism

This project in the Agraulis vanillae system was conducted in collaboration with former postdoc Wilnelia Recart Gonzalez, with funding from her NSF Postdoctoral Fellowship.  Working with an amazing team of undergraduate researchers, we have found that drought stress to larval food plants and virus exposure interact to affect morphology and behavior of the surviving insects, in ways that could impact their effectiveness as pollinators.  See poster below for some preliminary results.

Recart et al. ESA Poster – Sublethal Effects Agraulis + NPV Drought_8_5_22

Prior immunity and evolution of virulence in an emerging pathogen

Photo by D. Hawley

I am currently collaborating with Dana Hawley, Kate Langwig, and others on a project to study host prior immunity as a source of heterogeneity in Hawley’s house finch-mycoplasma system at Virginia Tech. We are using experimental data to model how repeated exposure to mycoplasma on bird feeders could contribute to disease population dynamics and the evolution of virulence in this emerging pathogen.  This work was funded by an EEID grant in 2021.  We will be hiring a quantitative biology postdoctoral scholar to work on fitting epidemiological models with continuous variation in host susceptibility, to start in 2023; please contact Arietta Fleming-Davies with questions or interest.

For more details, see:

Fleming-Davies, Arietta E.*, Paul D. Williams*, André A. Dhondt, Andrew P. Dobson, Wesley M. Hochachka, Ariel E. Leon, David H. Ley, Erik E. Osnas, and Dana M. Hawley. 2018. Incomplete host immunity favors the evolution of virulence in an emergent pathogen. Science, 359: 1030-1033.
*equally contributing authors

Processes maintaining diversity in an insect viral pathogen

I used a combination of field experiments and differential equation models to understand what maintains diversity in a pathogen that infects spongy moth larvae (Lymantria dispar, formerly ‘gypsy moth’) .  Phenotypic variation is common in most pathogens, yet the mechanisms that maintain this diversity are still poorly understood.  We found evidence that host heterogeneity in susceptibility may help maintain coexistence of multiple pathogen strains by introducing two alternate strategies for the pathogen: a low-transmission, low-variability strain is able to coexist with the high-transmission type favored by classical non-heterogeneity models.

In the same system, we found evidence of a cost of virulence in the overwinter environmental transmission that might also help maintain pathogen polymorphism.  This cost could impose an upper limit to virulence even in a highly virulent pathogen.

For more details, see:

Fleming-Davies, Arietta E., Vanja Dukic, Viggo Andreasen, and Greg Dwyer. 2015. Effects of host heterogeneity on pathogen diversity and evolution. Ecology Letters, 18:1252-1261.

Fleming-Davies, Arietta E. and Greg Dwyer. 2015. Phenotypic variation in environmental persistence of a baculovirus and the cost of virulence. The American Naturalist, 186:797-806.

Host-pathogen coevolution

Photo by B. Brachi

Phenotypic variation in a pathogen is closely tied to host-pathogen coevolution. I worked with a colleague and current collaborator, David Paez, to look at how exposure to different virus doses and isolates influences the life history of the spongy moth.  We are also interested in modeling within-host dynamics of this virus and host immune with partially observed Markov process models, in order to ask to what extent stochasticity in within-host processes leads to variation in pathogen and host fitness. Our work on host-pathogen coevolution also led to an independent project for an undergraduate student on detecting genotype by genotype interactions between host and pathogen in this system.