THE MITOCHONDRIAL-DNA MOLECULE OF SUMATRAN ORANGUTAN AND A MOLECULAR PROPOSAL FOR 2 (BORNEAN AND SUMATRAN) SPECIES OF ORANGUTAN

The complete mitochondrial DNA (mtDNA) molecule of Sumatran orangutan, plus the complete mitochondrial control region of another Sumatran sp ecimen and the control regions and five protein-coding genes of two sp ecimens of Bornean orangutan were sequenced and compared with a previo usly reported complete mtDNA of Bornean orangutan. The two orangutans are presently separated at the subspecies level. Comparison with five different species pairs-namely, harbor seal/grey seal, horse/donkey, f in whale/blue whale, common chimpanzee/pygmy chimpanzee, and Homo/comm on chimpanzee-showed that the molecular difference between Sumatran an d Bornean orangutan is much greater than that between the seals, and g reater than that between the two chimpanzees, but similar to that betw een the horse and the donkey and the fin and blue whales. Considering their limited morphological distinction the comparison revealed unexpe ctedly great molecular difference between the two orangutans. The nucl eotide difference between the orangutans is about 75% of that between Homo and the common chimpanzee, whereas the amino acid difference exce eds that between Homo and the common chimpanzee, On the basis of their molecular distinction we propose that the two orangutans should be re cognized as different species, Pongo pygmaeus, Bornean orangutan, and P. abelii, Sumatran orangutan.