TABLE 5

Robustness to population structure

Migration rateEmbedded Image Embedded Image ρ/θ in C.I.
6.25 × 10−6a0.270.2473
6.25 × 10−6b0.400.2586
2.5 × 10−5a0.630.4696
2.5 × 10−5b0.400.2991
2.5 × 10−4a0.480.3396
2.5 × 10−4b0.430.3797
  • Shown are the median of the MLE of ρ/θ; g, the proportion of times the MLE is within a factor of 2 of the truth; and coverage properties for the ~95% confidence interval for ρ/θ under population growth. Samples were simulated under a two-island model, with a diploid population size of 10,000 on each island, with migration rates of 6.25 × 10−6, 2.5 × 10−5, and 2.5 × 10−4 (these represent the fraction of each generation that are migrants).

  • a Twenty-five chromosomes sampled from each population.

  • b Fifty chromosomes sampled from a single population. Results are based on 100 simulated samples from each model, with r = μ = 2.5 × 10−5, so the true value of ρ/θ = 1.