Median-joining network of HVS-I sequences of haplogroup M12 and the spatial frequency distribution. The circles represent mtDNA HVS-I (16090 - 16365) sequence types, shaded according to region with an area proportional to their absolute frequency which is also indicated by the number in the circle. Mutations are transitions unless the base change is explicitly indicated. Heteroplasmic positions are indicated by an "H" after the nucleotide positions. Some HVS-II sites were employed to improve the resolution and were noted in parentheses.