Figure 2: Median-joining statistical parsimony network based on 797 bp of mitochondrial cyt b sequence data ( ) from Acanthurus nigroris sampled across the Pacific. Each circle represents a haplotype, and its size is proportional to its total frequency. Branches represent a single nucleotide change and black crossbars indicate unsampled haplotypes; colors denote collection location as indicated by the embedded key. It should be noted that there were no shared haplotypes between Hawaiian (including Johnston Atoll) and the remaining Pacific populations, which form two distinct clades separated by 25 mutational steps (corrected sequence divergence, ; [55]).