Map of sampling locations. Samples were collected from the western Atlantic (CAN), Greenland (GRE), northern Iceland (ICN), southern Iceland (ICS), the Faeroe Bank (FBA), the Faeroe Plateau (FPL), Norwegian coastal cod (NCC), Northeast Arctic cod (NEAC), northern North Sea (NNS), the English Channel (ECH), southern North Sea (SNS), central North Sea (CNS), Kattegat (KAT), Belt Sea (BES), western Baltic Sea (WBA), Arkona Basin (ARK) and the central Baltic Sea (BAS). Red stars indicate samples used in the global analyses, while yellow stars mark additional samples used in regional comparisons (see also Table 1). A bar chart shows allele frequencies in each of the eight samples used in the global analyses. Presented are global outlier loci identified by BAYESCAN along with a representative neutral locus, displaying a global FST corresponding to the global neutral FST (eight outlier loci removed, see Figure 2a)). Populations from left to right for each locus are CAN, GRE, ICS, NEAC, NCC, CNS, ECH, BAS.