|VOL. 23, NO. 2||September 12, 1997|
Melnick, Colleagues May Have Found a New Subspecies of Chimp
By John Kelly
olumbia's Don J. Melnick and a team of other New York City anthropologists has analyzed DNA from a chimpanzee population in southern Nigeria and western Cameroon, showing that the population is genetically distinct from the three recognized subspecies of common chimpanzee.
The preliminary finding, reported in a recent issue of the British journal Nature, means either that a new subspecies of chimpanzees has been discovered, or the existing division into three subspecies is erroneous and a new family tree must be devised, according to the researchers. Either result could require more aggressive conservation plans for the species, which is endangered the finding, the anthropologists suggest that the correct name for it is Pan troglodytes vellerosus.
"The fact that the Nigerian samples all sorted out together in our tree and that they were well separated from the other named clusters led us to the conclusion that we might have a new subspecies," Melnick said. "They are as clearly defined as the other named subspecies, so if this holds true with additional samples, you either collapse the other subspecies or name a new one."
The name has historical significance: the British explorer Sir Richard Burton collected a chimpanzee skin on an expedition to Mount Cameroon in 1861, and on receiving the skin J.E. Gray of the Natural History Museum in London dubbed the creature "vellerosus," possibly from the Latin vellereus, or "woolly." Burton's skin may have come from the same subspecies as that discovered by the New York researchers.
Field research was conducted in July and August of 1995 by Melnick, a molecular evolutionary geneticist, professor of anthropology and biological sciences at Columbia and director of the Center for Environmental Research and Conservation (CERC), based at Columbia, and by Katy Gonder, a graduate student at CUNY and a research associate in Hunter College's department of anthropology. Her research was guided by her thesis advisor, John Oates, professor of anthropology at Hunter and African forest primate ecologist; and Todd Disotell, assistant professor of anthropology at NYU and primate molecular geneticist. Gonder conducted her laboratory work and analysis both at NYU and with Columbia research scientists Michael Forstner and Juan Carlos Morales at CERC.
Three subspecies of common chimpanzee have been generally recognized, based on geographical, morphological and genetic criteria. Pan troglodytes verus is found in West Africa, Pan troglodytes troglodytes in Central Africa and Pan troglodytes schweinfurthii in East Africa. Though there are scattered groups of chimpanzees in Africa west of Ghana and east to Nigeria, all genetic samples of the verus subspecies prior to this study had come from west of Ghana, a factor that may account for their considerable genetic divergence from the others.
The study found as much difference between the Nigerian chimps and the verus subspecies as between the two other recognized subspecies. That result, in itself, is not enough to declare a new subspecies, the researchers said, but it does throw the existing schema into question. If the Nigerian chimpanzees turn out not to be sufficiently different to be regarded as a distinct subspecies, then the other groups of central and eastern chimpanzees now recognized as subspecies should only be considered populations of Pan troglodytes troglodytes, they said.
They propose two possible revisions to the existing schema, leaving either two or four subspecies. Either the Nigerian chimps would be grouped with the other West African chimps as two related populations, with the East and Central African chimps on a separate branch also as related populations. Or, the West African populations would form a separate branch, the Nigerian population a second and the Central and East African populations a third and fourth.
The researchers are members of the New York Consortium in Evolutionary Primatology, which groups biological anthropologists at Columbia, CUNY, NYU, the American Museum of Natural History and the Wildlife Conservation Society at the Bronx Zoo. Laboratory work was primarily supported by CERC's program in conservation genetics.