BEE: Unraveling the ecological and evolutionary factors shaping host-associated microbial communities

A major question in both ecology and evolution is: what factors shape microbial communities? Understanding the factors that shape microbial communities is important because microbes play key roles in ecosystem function and in human and animal health. Despite numerous studies, our understanding of what drives microbial community assembly, composition, and dynamics are still lacking. Our gap in knowledge is, in large part, due to a lack of integration between the fields of ecology and evolution. Because microbes evolve so quickly both ecological and evolutionary pressures must be considered when studying microbial communities. Environmental factors, species interactions, and evolutionary dynamics all play a role in shaping communities. However, the relative contributions of each of these factors in driving microbial community composition remain unclear. This research will combine concepts of ecology and evolution to investigate what drives the composition of animal-associated microbial communities using the honey bee as a model system. The honey bee is an ideal model system for addressing fundamental questions about animal-associated microbial community dynamics for several reasons: 1) there are only a few microbes that live inside the bee gut, 2) all honey bees worldwide contain the same microbes inside their gut, 3) honey bees are easy to experimentally manipulate, and 4) all gut microbes of honey bees are cultivable in the lab.

Key to this research is our ability to capture community dynamics not only at the species level (alpha and beta diversity), but also at the strain level. Artificially inseminated queen bees will be used to create genetically controlled colonies that will be used for in vivo experiments (natural and lab). Community dynamics will be followed across different controlled environmental conditions (i.e. different genetic backgrounds and lifestyles) in which a host-associated microbial community can develop. Results will determine how each of these ecological factors influence microbial composition. The role microbial competition or colonization order (i.e. neutral vs niche dynamics) plays in dictating the community composition will be assessed via in vivo co-colonization experiments. The entire gene content (i.e. functional capabilities) of microbial communities will be analyzed to test the functional equivalency hypothesis, which is at the cornerstone of the neutral theory in community ecology. Additionally, the extent of microevolution that occurs within a host, and how this impacts community structure over time will be evaluated. Age, lifestyle, and genetically controlled bees will be co-inoculated with defined communities (different combinations of strains and species) and temporally assessed for strain and community level changes. Unlike most microevolution studies which are done on single organisms under in vitro conditions, this project will follow evolutionary processes within a natural microbial community. Overall, this proposal will bridge ecology and evolution by integrating concepts and approaches from both fields to investigate the forces that govern the composition of host-associated microbial communities. The broader impacts of this proposal have three major components that are set in the context of an institution that is minority serving. The first (i) component is faculty and student participation in, and organization of, outreach events through formal partnerships between K-12 schools and informal outreach activities. The second (ii) component consist of curriculum development to create authentic classroom research experiences for undergraduates, and the third (iii) component involves research training for underrepresented minorities in science (URM).

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.