Milena Salgado-Lynn

Conservation of adaptive genetic diversity in primates of the Lower Kinabatangan Wildlife Sanctuary

The Lower Kinabatangan Wildlife Sanctuary (LKWS) is renowned for its rich primate diversity. However as the habitat is highly fragmented, primate populations are suffering from environmental pressures that could lead them to extinction. Previous genetic studies on orang-utans, long-tailed macaques and proboscis monkeys have focused on neutral genetic variation, showing high levels of genetic diversity. Except for the long-tailed macaques, the populations seem to have undergone expansions and in the case of orang-utans this seems to correlate with anthropogenic mediated environmental change. Nevertheless, neutral markers do not provide information about the response to selective environmental pressures and the fitness of the populations. Therefore, it is important to assess the adaptive genetic variability of populations prior to direct intervention. MHC (Major Histocompatibility Complex) genes have been used as adaptive markers because they are essential for antigen recognition among other selective functions. Previous studies have shown that specific MHC alleles could be associated to resistance or susceptibility to infectious diseases in the wild. Some examples are the resistance to strongyle nematodes in Soay sheep (Ovis aries L.) and the resistance of Atlantic salmon (Salmo salar) to Aeromonas salmonicida due to variations in MHC class II alleles. For conservation purposes, it is urgent to find out whether there are immunogenetic variants that may influence susceptibility to pathogens.

By investigating the extent of MHC variation for species which have undergone population bottlenecks, such as proboscis monkeys and orang-utans, we can gain an indirect insight into their potential resistance against various diseases, which could be of great importance for the re-establishment of self-sustained populations. There are still very few studies examining the genetic basis of resistance to naturally occurring pathogens in wild vertebrate populations and this will be the first genetic study in the region to address adaptive genetic diversity of three primate species. The information will be used to identify adaptive genetic differentiation between sub-populations and threats to genetic diversity in order to determine appropriate intervention measures to maintain gene flow and diversity between these sub-populations.

The main objective is to compare neutral with adaptive genetic variation of three primate species (orang-utan, proboscis monkeys and long-tailed macaques) within the LKWS, and correlate the level of adaptive variation with specific environmental pressures such as their parasitic fauna. The results will be incorporated into the conservation management plan of these primates to ensure their long term-survival.

Project Update: April 2008

Rosman. Fixing samples for parasite screening.

"The first sampling season was carried out between the months of October 2007 to March 2008. Over 560 feacal samples were collected from lots 1-4, assisted by Mr Rosman Sakong from Red Ape Encounters (community based ecotours), and Dr. Benoit Goossens from Cardiff University. Boat surveys were carried out during late evening and early morning to spot groups and collect samples, respectively. New fixation techniques for parasite screening were learnt and applied by Mr. Sakong and MSL. Additionally, sucrose flotation techniques were used to separate parasite eggs from faecal material and so far the presence of Trichuris spp. is evident in almost all the groups; hookworms are also quite conspicuous even though some data was lost during the optimisation of the technique, we are confident to have more consistent results during the next sampling season. Samples were stored for posterior genetic studies and nearly 240 were subjected to DNA extraction. At the time being, amplification of microsatellites in proboscis monkey samples is being optimised.

Personally, I would like to say that the degradation of the habitat is quite shocking. Most of the floodplain is covered by oil palm plantations in such a way that until a few kilometres from the river one thinks it’s the only type of vegetation. Hopefully, our results will be added to the conservation management plan and to the list of arguments to be used by the Malaysian government to buy the land back for the restoration of the Kinabatangan habitat."