Tree drawn from a median-joining network of 180 mtDNA haplotypes observed in Hainan Island. mtDNA motifs of HVS-I (16080-16488) combined with HVS-II and/or certain coding region sites were considered to improve the resolution of the tree which was constructed manually and checked by using the Network 4.510. The circles represent mtDNA sequence types, shaded according to population with an area proportional to their absolute frequency. The geographic sources of populations were also noted. These are transitions while suffixes A, C, G and T refer to transversions, "Y" specifies heteroplasmic status C/T at the site, and "@" means a reverse mutation. Seven haplotypes were determined as the existing of heteroplasmic sites.