NSF Postdoctoral Fellowship in Biology: Evolution of Increased Parasite Transmission Dispersion

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2022, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment and Phenotypes. The fellowship supports research and training of the Fellow that will contribute to the area of Rules of Life in innovative ways. This research aims to explain the phenomenon in epidemics known as transmission dispersion, where most new infections are transmitted from relatively few infected individuals. For example, roughly 10% of COVID-19 cases cause 80% of new COVID-19 cases. This variation could be due to differences among hosts, for example, in how much infected people cough. Most research to date has focused on variability in host responses to infections. However, the pathogen itself (e.g., SARS-CoV-2 virus) can also impact transmission dispersion. For example, distinct strains of pathogens can drive different numbers of new infections. Increases in the number of new hosts that pathogens transmit to is commonly a result of adaptive evolution (e.g., new SARS-CoV-2 variants). The Fellow hypothesizes that evolution can also increase transmission dispersion when pathogens adapt to variable host populations. Specifically, pathogens could adapt to specialize on highly infectious hosts. However, this might come at the cost of transmitting less effectively from the larger but less-infectious host group. In this way, pathogen adaptation could further skew transmission events so that most new infections are transmitted from a minority of infectious hosts. The study's results will help to predict when host variability drives the adaptation of pathogens with highly dispersed transmission; this will help to improve the accuracy of models that predict the course of epidemics. In addition, the Fellow will develop and teach educational modules on pathogen ecology and evolution to Philadelphia School System students with the aim of increasing students' sense of belonging and confidence in their abilities in science. The Fellow will determine whether parasite adaptation increases transmission dispersion by (1) developing mathematical models to generate theoretical predictions and (2) testing predictions using an experimental system based on the bacterium E. coli and its viral pathogen, phage lambda. Through this training, the Fellow will gain essential skills to establish a combined theoretical and experimental research program focused on parasite evolutionary ecology and epidemiological dynamics. Further, the Fellow's outreach skills will improve by developing and teaching educational modules on pathogen ecology and evolution to K-12 students that will increase their confidence in doing science. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.