NSF RUI: Characterizing Adaptation to Heterogenous and Stressful Environments

This project takes advantage of experimental evolution in which organisms are evolved in the laboratory under defined conditions. Experimental evolution has been especially successful with microorganisms because they can grow quickly to large population sizes, making the pace of evolution fast enough to study in short periods of time. In this case, the bacteria are propagated under defined but variable environmental conditions to mimic the stressors bacteria encounter in nature.

This project aims to characterize the role of gene expression in adaptation and evolution by focusing on the role of genes that can affect cellular behavior by regulating other genes. Mutations in regulatory genes may be particularly advantageous for bacteria in changing environments. This work will be performed in collaboration with undergraduate students at a Hispanic and Minority Serving Institution where almost 90% of students are from groups underrepresented in STEM.

Further, the PI will integrate this project into an upper-division microbiology course as an authentic research experience for 48 undergraduate students per year, and perform outreach activities related to this project with K-12 educators. In these ways, the research will help to increase the diversity of students entering the STEM pipeline and leave them better prepared for roles in STEM fields.

Changes in gene regulation are a driving force for evolution. Cis regulatory elements are often the cause of evolutionary change when comparing different species, whereas trans regulatory elements are often altered when organisms need to adapt to changing environments. Experimental evolution studies with microbes have begun to probe the role of these factors, but often in unchanging environments where either functional or cis regulatory changes would be favored.

The PI will explore the role trans regulatory elements play in adaptation to a heterogeneous environment by first identifying each trans regulatory factor that affects survival of Escherichia coli in long-term cultures in complex media. Then, the PI will characterize the role of these trans regulatory factors in adaptation, by first correlating the genotype with the transcriptome of the population to identify gene expression changes, and determine which of those changes confer the growth phenotype.

The PI will then perform experimental evolution on mutant cells to determine how these mutations may change the evolutionary pathways cells can use to adapt to a heterogeneous environment. Understanding how these types of regulatory changes affect adaptation will contribute to the fundamental understanding of evolutionary principles.

This research is funded by the Genetic Mechanisms program in the Division of Molecular and Cellular Biosciences in the Directorate of Biological Sciences.

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.