Fig. 1.

Schematic of the model and the question-of-interest. a) Whenever a cell divides, there is a probability ${\mu }_b(x)$ of it gaining a beneficial mutation which can depend on the fitness x of the cell. When a beneficial mutation occurs, we assume that the selection coefficient s of the mutation is drawn from some normalized distribution ${\rho }_n(s|x)$ which can also depend on x. The overall distribution $\rho (s|x)$ of beneficial selection coefficients when a mutation occurs specifies the fitness-parameterized landscape, or equivalently, the form of macroscopic epistasis. b) Clonal interference refers to the phenomenon where a mutant (“A,” already growing exponentially in size) is out-competed by a new mutant (“B”) with a higher selective advantage. c) The functional forms of the average fitness trajectories F(t) are compared after rescaling time such that the initial adaptation speeds are identical. We ask whether clonal interference speeds up (left) or slows down (right) the functional form of the average fitness trajectory, and how this depends on $\rho (s|F)$.