Figure 2.
The probability of neofunctionalization of a newly arisen duplicate gene scaled to the neutral expectation (θ), as a function of the effective population size (N), number of potentially participating amino acid sites in the new two-residue function (n), and the selective advantage of the new function (s). For the solid lines, s=0.01; for the dashed lines, s=0.0001. In all cases, the mutation rate to null alleles (μ) is 10−6, and the nonsynonymous mutation rate per codon (v0) is 10−8. Each data point is derived from 107 to 1010 stochastic simulations. The solid and dashed lines are the analytical approximations described in the text. The dotted line denotes the point at which the probability of neofunctionalization is equal to the fixation probability of a neutral mutation.