Maximum likelihood estimates of proposed distributions of deleterious fitness effects of new nonsynonymous mutations.

ML estimates and predicted number of human-chimp fixed differences under each model computed after applying demographic correction. Distributions are in terms of the scaled selection coefficient, �� = 2Ncurrs, where Ncurr is 25,636 in African Americans and 52,907 in European Americans. ��LL is the likelihood difference between the model and the overall best-fit model for the population; # fixed is the number of nonsynonymous fixed differences predicted by the model. Approximate 95% confidence intervals based on semi-parametric bootstrap are reported for African American parameter estimates.