Chimpanzee populations living in relatively close proximity are substantially more different genetically than humans living on different continents, according to a study published today in PLoS Genetics. The study suggests that genomics can provide a valuable new tool for use in chimpanzee conservation, with the potential to identify the population of origin of an individual chimpanzee or the provenance of a sample of bush meat.
Common chimpanzees in equatorial Africa have long been recognized as falling into three distinct populations, or sub-species: western, central and eastern chimpanzees. A fourth group, the Cameroonian chimpanzee, has been proposed to live in southern Nigeria and western Cameroon, but there has been considerable controversy as to whether it constitutes a distinct group.
Scientists from the Universities of Oxford and Cambridge, the Broad Institute, the Centre Pasteur du Cameroun and the Biomedical Primate Research Centre examined DNA from 54 chimpanzees, measuring the DNA at 818 positions across the genome that varied between individuals. Analysis of patterns in the data showed Cameroonian chimpanzees to be distinct from the other, well-established groups. Intriguingly, previous conclusions based on earlier studies, that Cameroonian and western chimpanzees were most closely related, were shown to be untrue; instead the closest relationships to Cameroonian chimpanzees are with nearby central chimpanzees.
Dr Rory Bowden from the University of Oxford, who led the study, said: "These findings have important consequences for conservation. All great ape populations face unparalleled challenges from habitat loss, hunting and emerging infections, and conservation strategies need to be based on sound understanding of the underlying population structure. The fact that all four recognized populations of chimpanzees are genetically distinct emphasizes the value of conserving them independently.
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