Although in some species of microbes all the individuals are very similar, there are many species in which individuals are very different in how they live, what they look like, and the genomes that determine these things, because they have different evolutionary histories. These differences in evolutionary history can come from having inherited small changes in their gene sequences, or because they don't share all the same genes across their genomes. Determining why genomes within a species vary, and what the consequences of this variability are is important in understanding microbial diversity on Earth. It will help us better understand what knowing the species a microbe belongs to can tell us about how it will evolve or respond to environmental conditions. This fundamental biological question has practical implications for questions about the role of microbes in agriculture and public health. This research will also provide an important platform for training undergraduates, graduate students, and the postdoctoral scholars. Through its integrated educational plan, it will help provide interdisciplinary training in analyzing large-scale genomic data, a much-needed skill set. This will be done by involving students in the research, though hands-on undergraduate courses, and through teacher training and a microbial art exhibit.
Species delineations and the mechanisms of speciation have been notoriously challenging to study in microbes owing to pervasive horizontal gene flow, within-species variation, and cryptic ecological niches that structure microbial populations. This research will test the hypothesis that different components of the bacterial genome diversify through distinct mechanisms, which can facilitate ecological adaptation across different time scales. Using Streptomyces as a model system, this research will use genomic sequences from more than 1,500 free-living and host-associated Streptomyces isolates from disparate environments, and integrate data on three facets of genomic heterogeneity: distribution of genetic variants, rate of gene content changes and signals of selection and neutrality. Completion of the project will reveal the extent to which a single genome carries genes with distinct ecologies and modes of evolution, and how this genomic heterogeneity contributes to success and survival in specific environments. Output from the proposed project will advance our knowledge of the origins, extent and impacts of genomic heterogeneity on microbial evolution, divergence and adaptation.
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.
