Figure 1.—

An illustration of the general bottleneck/expansion demographic model used to test various population genetics statistics of high-F_ST fragments (see Table 5 for specific parameters and results). Initial effective population size in Africa (N_i) is assumed to be constant over time (see Haddrill et al. 2005; Thornton and Andolfatto 2006). N_b is the effective population size of the bottlenecked population derived from Africa T_b generations ago. At T_r, the derived U.S. population is assumed to experience a recovery with an exponential growth to the present effective population size, N_o. The duration time from T_b to T_r is referred to as d. Migration rate between Africa and the United States is assumed to be effectively zero after T_b to the present (see text).