Speciation and intrasubspecific variation of Bornean orangutans, Pongo pygmaeus pygmaeus

Mitochondrial DNA control region sequences of orangutans (Pongo pygmaeus) f rom six different populations on the island of Borneo were determined and a nalyzed for evidence of regional diversity and were compared separately wit h orangutans from the island of Sumatra. Within the Bornean population, fou r distinct subpopulations were identified. Furthermore, the results of this study revealed marked divergence, supportive evidence of speciation betwee n Sumatran and Bornean orangutans. This study demonstrates that, as an enti re population, Bornean orangutans have not experienced a serious genetic bo ttleneck, which has been suggested as the cause of low diversity in humans and east African chimpanzees. Based on these new data, it is estimated that Bornean and Sumatran orangutans diverged approximately 1.1 MYA and that th e four distinct Bornean populations diverged 860,000 years ago. These findi ngs have important implications for management, breeding, and reintroductio n practices in orangutan conservation efforts.