For the first time ever, an EU-funded international consortium of scientists has decoded the entire genome of our orange-haired relative, the orang-utan. Their research, published in the journal Nature, showcases the immense genetic diversity in Indonesia's orang-utan, and reveals intriguing clues about the evolution of great apes, including humans.
The study was funded in part by two EU projects: ALGGENOMES ('Algorithms for analysis of genes and genomes') and BIOSEQANALYSIS (Computational methods for biological sequence analysis with application to evolution of yeast mitochondrial genomes'). Each project received a Marie Curie International Re-integration Grant worth EUR 100,000 under the Seventh Framework Programme (FP7).
Rich genetic diversity is expected to enhance the ability of populations to stay healthy and adapt to changes in the environment. However, looking at the genetic diversity of two orang-utan species -Sumatran and Bornean - brought about some very counterintuitive observations for the consortium.
The population from Borneo, found to have very limited diversity in its gene pool and a condensed habitat, has a larger census population of 50,000. By contrast, genetic diversity has not been lost in the Sumatran orang-utans, which have a more widespread habitat. But their census population was decreased to only around 7,000. Nonetheless, the orang-utan genome had yet another big surprise.
The Sumatran and Bornean orang-utans have been physically separated for at least 21,000 years - the last time land bridges existed between the 2 islands. Earlier studies estimated that they became distinct species more than 1 million years ago. But the analysis of the entire genome rewrote history; it appears that they parted ways just 400,000 years ago.
More surprises came as geneticists compared the genome of orang-utans with that of other great apes. Orang-utans originated some 12 to 16 million years ago, giving their genome much more time to evolve than that of chimpanzees and humans, which split into their own lineages 5 to 6 million years ago. But a comparison of the three genomes showed that the latter lose and gain new genes at twice the rate of orang-utans.
Co-author Dr Carolin Kosiol from the University of Veterinary Medicine in Vienna, Austria examined a total of 14,000 human genes that are also found in the orang-utan, chimpanzee and macaque. Her findings revealed that, during their evolution, genes involved in two processes have been particularly influenced by natural selection: visual perception and the metabolism of glycolipids.
Specifically, genes involved in glycolipid metabolism, the chemical breakdown of molecules including fats for the production of energy, evolved more quickly than expected. This disparity could be attributed to orang-utans evolving differently in order to minimise the mobility of genetic agents that could cause disease.
In humans, a number of inherited neurogenerative disorders have already been associated with defects in cholesterol and glycolipid metabolism. 'Changes in lipid metabolism may have played a big part in neurological evolution in primates, as well as being involved in the diversity of diets and life history strategies,' Dr Kosiol says.
The orang-utan joined chimpanzees and humans as the third great ape to have its genome sequenced. Still, 'it would be very valuable to sequence more primate genomes to enable more comparative analysis of this kind and thus help us understand the evolution of primates and our own species,' comments Dr Kosiol.
Further research aiming to sequence the genome of two more great apes, gorillas and bonobos is currently under way.
Category: Project results
Data Source Provider: University of Veterinary Medicine; Nature
Document Reference: Locke, D.P., et al. (2011) Comparative and demographic analysis of orang-utan genomes. Nature, published on 27 January. DOI: 10.1038/nature09687.
Programme or Service Acronym: FP7, FP7, FP7-PEOPLE
Subject Index : Scientific Research; Coordination, Cooperation; Medical biotechnology; Veterinary and animal sciences