Bayesian clustering of individuals. Bayesian clustering of all individuals using STRUCTURE 2.2 [51,52], assuming four different clusters of individuals (k = 4), an admixture model and no prior population information. Each horizontal bar denotes an individual, and the four colours denote the different inferred clusters. NSH denotes North Sea houting, whereas ELW denotes European lake whitefish populations. See Table 1 for a list of sample abbreviations.