Historical effective population sizes and migration rates. Map with superimposed historical effective population size estimates (θ) of the sampled indigenous Coregonus populations. Gene flow estimates (M) and the direction of gene flow are indicated by arrows. Punctuated green arrows indicate 10 = M < 15, blue arrows indicate 15 = M < 20 and red arrows indicate M = 20. Estimates of M < 10 are not shown. See Additional file 2 for an overview of all θ and M values and their associated 95% confidence intervals. The analyses were conducted using the method and software MIGRATE 2.0.3 .