Geographic barriers were computed with the Barrier v2.2 software [32]. For the geographic positioning of samples the great-circle coordinates of the respective capital of the country of origin, or the city where an individual population sample had been recruited was used. The Fst pair-wise comparison matrix for genetic and geographic distance was used in barrier analyzes. The geographic location of the CEU sample was approximated by Northern Germany (as shown in the Lao et al. 2008 paper). The geographic distances between the above mentioned cities were used to calculate the correlation coefficient between geography and statistics, like Fst and inflation factor λ. Statistical tests were performed in R v2.8.1 (www.R-project.org).
