Figure 2

Types of selection against mutations with variable degrees of synergistic epistasis (after Redfield, 1994). The vertical axis shows the relative fitness of an individual with i deleterious mutations compared to an individual with no deleterious mutations. Independent selection (no epistasis): relative fitness W _i = 0.9ⁱ. Quadratic selection (medium epistasis): W _i = 1-0.014i - 0.0112i² [38]. Truncation selection (high epistasis): W _i = 1 if i < = 7, else W _i = 0.