Fig. 5

Empirical and simulated geographic patterns of introgression. a For each of the ten samples, the empirical (top row) and simulated (for simulation parameter set par2; bottom row) proportions of the nuclear genome introgressed (y-axis) is plotted against distance to the southernmost sample (x-axis). In the left panels, all samples are considered, in the central panels only the five southern ones, and in the right panels only the five northern ones. Dashed lines represent linear regression trendlines. b Empirical [45] and simulated mitochondrial DNA introgression frequencies in the ten sampled localities, ordered from Southwest (ALT) to Northeast (NAV). For the simulated data, dots depict the median introgression frequency value per population based on 1000 simulations and vertical lines represent 1.5 × interquartile range (IQR) extensions