Genetic Tools for the Captive Conservation Management of Gibbons

The gibbons (Hylobatidae) are 20 species of primate native to South-east Asia. All species are listed as Vulnerable by the IUCN. One of the measures employed in their conservation are global captive breeding programmes, managed in Europe by the European Association of Zoos and Aquaria (EAZA).

As captive populations are small and largely closed, they are vulnerable to inbreeding and loss of genetic diversity. These processes can be detrimental to the animals as health issues develop, and reduce the chances of long-term survival of the species. A microsatellite panel of 12 variable nuclear loci was developed, successfully generating profiles on all species tested (n=11). A general trend of loss of genetic diversity and heterozygosity was seen in the EAZA populations, though this varied by species. Inbreeding was detected in the Symphalangus syndactylus population. Comparisons with samples from the University of Tokyo indicate the EAZA collection does not possess the range of genetic diversity present in these species. The panel was also used to resolve a case of uncertain paternity. Additionally, some loci appear to have species-specific alleles, providing utility in species identification.

Gibbon species within genera are able to hybridise to produce viable offspring. Furthermore, some gibbon species are difficult to distinguish phenotypically. This issue is compounded by recent changes in the gibbon taxonomy, sometimes long after individuals were taken from the wild. This raises the possibility of cryptic hybrids within the captive populations, threatening the genetic integrity of those species groups. Phylogenetic methods and analysis of newly identified transposable element insertion loci were used to genetically identify gibbon species. Mixed-species ancestry was revealed in four lineages in the EAZA collection, and five in the Tokyo samples. These tools are not only of benefit to captive breeding institutions, but also rescue centres and researchers.