A Neighbor-Joining tree is based on genetic distances (% observed differences / total length of sequence) between all pairwise combinations of seals. Branch lengths in the tree are proportional to the amount of inferred change on each. Statistical support for each branching is based on "Bootstrap Re-sampling", the number of times it appears in 10,000 random re-samplings of the total sequence. Lettered groups are the statistically support clades (groups of related individuals, including their common ancestor). The most inclusive clade (A) includes five sub-clades 1 - 5. Color-codes for population are as given in Figure 1: SG = Southern Gulf of St Lawrence, NL = Newfoundland Ice Front, NL' = second Ice Front sample, GS = Greenland Sea, Jan Mayen Is., WS = White Sea.