Drinking from the cup of adaptive landscapes: modeling a phenotypic fitness landscape of gene expression to predict epistasis between beneficial mutations.
This image shows a "landscape" carved into a 40-year old pottery mug made by the corresponding author's father. It is reminiscent of the metaphor of adaptive landscapes used to derive intuition about how populations evolve. We examined a series of strains with beneficial mutations affecting the expression of a metabolic pathway under selection. By developing a mathematical model based upon enzyme catalysis and costs of expression – parameterized to single mutants – we could predict the often antagonistic effects of combining beneficial mutations that were individually beneficial. See Chou et al.
Image Credit: Christopher J. Marx