Abstract
This study presents that the use of the whole mitochondrial genome sequence can resolve the phylogeny and the divergence history of the gibbons (Hylobatidae), which could not be achieved by the partial mitochondrial genome sequences. We newly determined the whole mitochondrial genome sequences of four gibbon species among three genera (Hylobates agilis, H. pileatus, Nomascus sp. and Symphalangus syndactylus). Adding a published sequence of H. lar to our new data set, we obtained a highly reliable phylogenetic tree of these five gibbon species, which enabled us to estimate their divergence dates. Divergence of the three genera occurred in the late Miocene; Nomascus diverged from the others about 8.0 million years ago (MYA) and Symphalangus and Hylobates diverged each other about 7.0 MYA. Among the Hylobates group, divergence may have took place in the Pliocene, 3.3-3.9 MYA, in the order of H. pileatus, H. lar and H. agilis. These results support the generic rank of Nomascus, Symphalangus and Hylobates in terms of the divergence dates. We propose a new scenario for the speciation of Hylobates: Hylobates gibbons' common ancestor spread over the Sundaland before climate changes in the Pliocene, which induced the fragmentation of rainforests and triggered the speciation of Hylobates gibbons.
