Phylogenetic tree based on complete U6 mtDNA genome sequences. A U5b individual has been added in order to root the tree. Nomenclature of individuals as in Table 2. Numbers along links refer to nucleotide positions; suffixes are transversions; i insertions and dd deletion of two nucleotides. Underlining indicates recurrent mutations in U6 subhaplogroup. U presents the following mutations with respect to rCRS: 73, 263, 311i, 750, 1438, 2706, 4769, 7028, 8860, 11467, 11719, 12308, 12372, 14766 and 15326.