FIG. 4.—

The effect of population size on duplicate retention is shown. The black and green lines refer to the neutral model for population sizes 1,000 and 100, respectively. The red line shows dosage balance for a population size of 1,000, whereas the blue line shows that of population size 100. Whereas the duplicate retention under the neutral model behaves similarly between the two population sizes, dosage balance–driven loss is much more deterministic for the larger population size due to higher effectiveness of selection (Pr(lose gene) = 0.0001; Pr(lose link) = 0.005). The fitness penalty for links out-of-balance is 0.4. These curves were generated using the parameter values in table 1 for the network model and were fit with the parameter values from the loss model in table 2.