Abstract

• The white-handed gibbon or Hylobates lar is currently classified as Endangered on the IUCN Red List of Threatened Species. Although the total population size is not small, forest fragmentation by human activity has affected the stability of local populations. To uncover the effects of forest fragmentation on the conservation of local white-handed gibbon populations, this study assessed the genetic status of an isolated white-handed gibbon population living in Ywar Kaing Kaung (YKK) village, Kayin State, Myanmar, where 26 individuals were living in nine groups. 631-bp nucleotide sequence consisting of the hypervariable region I (HVR-I) of mitochondrial DNA was analysed. Sequences were determined in nine of 18 samples from adult individuals. Among those, two haplotypes were found. Phylogenetic trees and a haplotype network uncovered that both haplotypes observed in YKK clustered with those of white-handed gibbons living in central Thailand, a subspecies H. lar entelloides. Haplotype diversity of the YKK population was low (0.556) compared with those of a white-handed gibbon population in Khao Yai National Park (KYNP), Thailand (0.823) and those of a siamang population in Sumatra, Indonesia (0.886), which suggested the strong bottleneck effect on the YKK population. On the other hand, nucleotide diversity was comparable (0.00357) with that of the KYNP population (0.00238). The low genetic diversity of the YKK population suggested the importance of genetic management at the local population level in white-handed gibbons.