Figure 1.

Nuclear SNP phylogeny of 43 individuals assigned to 5 populations (10 resident, 10 transient, 7 offshore, 10 Marion Island and 6 North Atlantic) based on 1346 SNPs. Maximum-clade-credibility tree shown in the black right-angled tree with posterior probabilities at nodes. Branch width is proportional to theta. Tree cloud produced using DENSITREE of the last 50 trees (representing samples taken every 1000 MCMC steps from 500 000 iterations) from SNAPP analysis visualise the range of alternative topologies. For this subsample (5), a total of four topologies were found within the 95% HPD (see Supplementary Table S3).