Figure 1.—

Influence of gene flow and genetic diversity in the detection of bottlenecks—posteriors. Posterior distributions were obtained for log₁₀(r), where r is the ratio of present (N₀) over ancient (N₁) population size change. Negative and positive values of log₁₀(r) correspond to population bottlenecks and expansions, respectively. For all analyses the prior for log₁₀(r) was a uniform between −5 and 5 and is represented by the horizontal dashed line. The results were obtained with five loci and 50 diploid individuals sampled from a single deme assuming a 100-island model (see text for details). (a) Posteriors obtained for all the simulations performed for M = 99 (i.e., F_ST = 0.01) and for θ = 1 (solid lines) and θ = 10 (dashed lines). (b) Same as in a, but for M = 19 (i.e., F_ST = 0.05). (c) Same as in a, but for M = 9 (i.e., F_ST = 0.10). (d) Same as in a, but for M = 3 (i.e., F_ST = 0.25). Most posterior distributions are shifted to the left but are in general relatively flat for high levels of gene flow and not very different from the prior. Posteriors indicating a potential bottleneck were obtained for the lowest levels of gene flow and the highest genetic.