Date of Award
Program or Major
Master of Science
Vaughn S Cooper
Phenotypic plasticity, epistasis or both are expected to influence the adaptive value of mutations and, by extension, how organisms adapt to new environments. We investigated interactions among five mutations that arose and fixed in a laboratory-evolved population of E. coli in a variety of different external environments. Overall, we found that positive pleiotropy tended to be positive rather than antagonistic and that epistatic interactions were common regardless of the external environment. The nature of the epistatic interactions depended strongly on the external environment and altered which adaptive paths were selectively accessible. Ultimately, achieving high fitness in a new environment was not due to synergistic interactions occurring between new beneficial mutations. Rather, new mutations that minimize antagonistic epistatic interactions while also improving fitness overall are most favorable. Thus, the fate of a new mutation does not solely depend on its individual fitness effect, but also its genetic and environmental contexts.
Flynn, Kenneth Mark, "Interactions between adaptive mutations in the environment and the consequences for adaptation in Escherichia coli" (2011). Master's Theses and Capstones. 630.