Orangutan DNA More Diverse Than Human's, Remarkably Stable Through the Ages
ScienceDaily (Jan. 26, 2011) — Among great apes, orangutans are humans' most distant cousins. These tree dwellers sport a coat of fine reddish hair and have long been endangered in their native habitats in the rainforests of Sumatra and Borneo in Southeast Asia.
In the Malay language, orang-utan means "man of the forest." Washington University scientists led an international project to sequence the orangutan genome. The work is expected to aid conservation efforts and the study of human evolution. (Credit: Perry van Duijnhoven/Carel van Schaik)
Now, an international team of scientists, led by Washington University School of Medicine in St. Louis, has decoded, or sequenced, the DNA of a Sumatran orangutan. With this genome as a reference, the scientists then sequenced the genomes of five additional Sumatran and five Bornean orangutans.
Their research, published Jan. 27 inNature, reveals intriguing clues about the evolution of great apes, including humans, and showcases the immense genetic diversity across and within Sumatran and Bornean orangutans. Diversity is important because it enhances the ability of populations to stay healthy and adapt to changes in the environment.
"The average orangutan is more diverse -- genetically speaking -- than the average human," says lead author Devin Locke, PhD, an evolutionary geneticist at Washington University's Genome Center. "We found deep diversity in both Bornean and Sumatran orangutans, but it's unclear whether this level of diversity can be maintained in light of continued widespread deforestation."
The scientists catalogued some 13 million DNA variations in the orangutans. This valuable resource can help conservationists assess the genetic diversity of orangutan populations both in the wild and in captivity and help set priorities for aiding subpopulations based on their genetic health.
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Comparative and demographic analysis of orang-utan genomes
Devin P. Locke et al
Nature 469, 529–533 (27 January 2011) doi:10.1038/nature09687
'Orang-utan' is derived from a Malay term meaning ‘man of the forest’ and aptly describes the southeast Asian great apes native to Sumatra and Borneo. The orang-utan species, Pongo abelii (Sumatran) andPongo pygmaeus (Bornean), are the most phylogenetically distant great apes from humans, thereby providing an informative perspective on hominid evolution. Here we present a Sumatran orang-utan draft genome assembly and short read sequence data from five Sumatran and five Bornean orang-utan genomes. Our analyses reveal that, compared to other primates, the orang-utan genome has many unique features. Structural evolution of the orang-utan genome has proceeded much more slowly than other great apes, evidenced by fewer rearrangements, less segmental duplication, a lower rate of gene family turnover and surprisingly quiescent Alu repeats, which have played a major role in restructuring other primate genomes. We also describe a primate polymorphic neocentromere, found in both Pongo species, emphasizing the gradual evolution of orang-utan genome structure. Orang-utans have extremely low energy usage for a eutherian mammal1, far lower than their hominid relatives. Adding their genome to the repertoire of sequenced primates illuminates new signals of positive selection in several pathways including glycolipid metabolism. From the population perspective, both Pongospecies are deeply diverse; however, Sumatran individuals possess greater diversity than their Bornean counterparts, and more species-specific variation. Our estimate of Bornean/Sumatran speciation time, 400,000 years ago, is more recent than most previous studies and underscores the complexity of the orang-utan speciation process. Despite a smaller modern census population size, the Sumatran effective population size (Ne) expanded exponentially relative to the ancestralNe after the split, while Bornean Ne declined over the same period. Overall, the resources and analyses presented here offer new opportunities in evolutionary genomics, insights into hominid biology, and an extensive database of variation for conservation efforts.
Subject terms:
Genetics and genomics, Evolution, Genetics and genomics, Organismal biology
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