There are four genetically distinct chimpanzee populations, all found in two relatively small regions of Africa. And yet these populations, which are sometimes less than a mile apart, are more genetically diverse than humans that live on different continents.
Three of the common chimpanzee groups are found in very close quarters, as you can see in the map below. While the distinct bonobo subspecies in in red on the southern side of the Congo River, the Eastern, Central, and Cameroonian subspecies form a nearly contiguous region in Central Africa, with only the Western population isolated from the others by any considerable geographic distance.
That's why the results of a new genomic study conducted by an international team of researchers is so surprising. Based on the DNA from 54 chimps taken from across these four populations, these chimps really are genetically distinct from each other despite often being so close together. What's more, the genetic diversity of these different chimp populations, even those who are practically right on top of each other, is significantly greater than that found in humans separated by entire continents. Oxford professor Peter Donnelly explains:
"Relatively small numbers of humans left Africa 50,000-100,000 years ago. All non-African populations descended from them, and are reasonably similar genetically. That chimpanzees from habitats in the same country, separated only by a river, are more distinct than humans from different continents is really interesting. It speaks to the great genetic similarities between human populations, and to much more stability, and less interbreeding, over hundreds of thousands of years, in the chimpanzee groups."
The high level of diversity also adds another wrinkle to ongoing chimp conservation efforts. Until now, it wasn't clear just how distinct the different sub-species really were - in particular, there was considerable debate whether the Cameroonian chimps really represented a separate group or not - and now we know that these really are very different groups of chimps, and we probably need to adjust our conservation plans according, as study leader Dr. Rory Bowden explains:
"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. Genomics can also provide tools for use in chimpanzee conservation. Genetic tests could cheaply and easily identify the population of origin of an individual chimpanzee or even a sample of bush meat."