NSF Postdoctoral Fellowship in Biology FY 2021: From parasitism to mutualism in a Wolbachia-Drosophila symbiosis

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This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2021, 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. Animal-microbe symbioses are ubiquitous in nature and are found in biological processes that include host immunity, development, nutrition, and fertility. Many mutualisms are thought to have developed from parasitic relationships but it is rare to find a symbiosis at the transition point between these states. The Fellow will investigate a symbiosis wherein previously parasitic bacteria of fruit flies have now developed a dual parasitic-mutualistic relationship with the host. While maintaining the ability to kill male hosts (male-killing), the strain is also required for host development. This system represents a unique opportunity to study a mutualism at a symbiotic transition point, allowing the Fellow to investigate the genetic basis for the change and in what contexts this condition may develop. The work includes outreach to local students from diverse backgrounds through a database of online, low-cost activities that teach important scientific concepts.The Fellow will address this research topic by performing experiments with a strain of Drosophila bifasciata infected with male-killing Wolbachia to address two main points: the genetic basis of this symbiotic transition and the contexts in which dual male-killer-mutualists successfully invade a population. The hypothesis is that the infected host strain has developed a critical developmental defect that is rescued by the parasite. To address the first question, the Fellow will perform comparative genomics on the infected host strain and an uninfected strain using fluorescence microscopy, gene expression analysis, and trans-infection experiments to identify the hypothesized host defect(s) at genetic and cellular levels. To address the second question, the Fellow will use theoretical population genetic modeling, experimental cage experiments, and population genetics of wild-caught D. bifasciata flies to determine the conditions in which a dual mutualist-male-killer may succeed in a mixed population. This work will be completed with training from Drs. Robert Unckless and Erik Lundquist at the University of Kansas and will focus on population genetics, bioinformatics, theoretical modeling, and microscopy. The research is complemented by development of a local program where diverse scientists will engage local kids in games and activities that teach scientific concepts and that will be available to anyone online.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.