Microsatellite DNA variation in Bornean orangutans (Pongo pygmaeus)

Orangutans (Pongo pygmaeus) on the islands of Borneo and Sumatra are consid ered two separate subspecies. However, the genetic relationships between is olated populations on Borneo are not clear. This study determined the exten t of variation within the Bornean subspecies of orangutan, using microsatel lite DNA analysis. Blood samples were collected from 96 individuals of know n origin from East, West and Central Kalimantan. Human microsatellite prime r pairs located at human map position D2S141, D4S431; D11S925, D16S420 and D17S791 were suitable for use in primates. D4S431 appeared monomorphic for all orangutans. In three cases (D2S141 East and West and D16S420 West), a h ighly significant excess of homozygous allele Frequencies was detected, but with other primer pairs no significant difference in allele frequencies oc curred. We conclude that the divergence between the different populations o n Borneo is less than the variation within the populations. There was also evidence that inbreeding occurred within the populations.