Figure 2. Population structure analysis of 11,457 neutral and 143 outlier SNPs for the intertidal gastropod Steromphala umbilicalis in the UK and Ireland. (A) Heatmap based on pairwise FST values across sampling sites (neutral SNPs = below diagonal; outlier SNPs = above diagonal). Non-significant pairwise comparisons are indicated with a black dot (P>0.001). The distribution of population structure for K=4 adaptive genetic clusters (outlier SNPs) is shown using TESS3 (B) and DAPC (C). Online version in colour.