U.S. and Kenyan scientists have identified a new elephant species. Their assessment of African elephants reveals that those living in rainforests are genetically distinct from the bigger ones roaming the grasslands as distinct as lions and tigers are from each other among cats.
For decades, many naturalists have called for re-classification of the African forest elephant. It is smaller than its free-ranging savannah counterpart. Its tusks are longer, thinner, and straighter, with a suggestion of pink to them. Its skull shape is also different. But appearance alone was insufficient to prove they were a different species, as University of Washington conservation biologist Samuel Wasser points out. "Those kinds of things people have argued could be due to diet differences just living in the forest," he said. "A pygmy, for example, is much, much smaller than many of the surrounding African tribes, but it doesn't make him a separate species."
Now, a new genetic study from the U.S. National Cancer Institute and Kenya's Mpala Research Center vindicates the notion of two separate African elephant species. Cancer Institute geneticist Stephen O'Brien and colleagues analyzed the chemical composition of four genes from cells in skin patches taken from 195 elephants in 21 different populations. "We were able to discover that they were really quite different between the savannah groups and the forest groups, but within the two groups they were very similar," he said.
Mr. O'Brien's team reports in the journal Science that the genetic difference between the two animals is nearly 60 percent as great as the difference between African and Asian elephants. Based on that degree of difference, they conclude that the forest and savannah elephants split from a common ancestor about two and a half million years ago. "That level of genetic difference in time is very consistent with it being a proper species, having adapted to different ecological strategies, to different habitats," said Mr. O'Brien. "Its comparable to the distance that we see between species everybody recognizes, such as the difference between lions and tigers or jaguars or leopards."
The study shows that the two elephants have retained their genetic distinction by very little cross-breeding.
The University of Washington's Samuel Wasser agrees with the genetic re-classification. "When you now are able to apply the more quantitative differences that genetics provides, it becomes very, very clear that there are such dramatic genetic differences, that classifying them as separate species is most certainly warranted," said Mr. Wasser.
The re-classification has implications for the conservation of the two elephant species. It divides what had been thought to be a single population of 500,000 elephants into two smaller groups making each rarer and more endangered. Stephen O'Brien says there must now be different approaches to saving them. "That we actually have two separate species, rather than one, means that they have become adapted to different habitats, and rather than just lump them all together and try to design a conservation plan that fits everybody, I now think it probably would be useful to develop two different ones," he said.
The forest elephants are the fewer just 150,000 in number. Samuel Wasser says they face the greater threat from logging, mining, development, poaching, and wars. He worries that their classification as a distinct species means less protection, because they are not yet covered separately in the Convention on International Trade in Endangered Species, known by the acronym CITES.
"It's vital that CITES enact legislation that will assure that the forest elephant remains protected, because, in fact, there are a third as many forest elephants as there are savannah elephants, and they are very, very important to protect," he said.
Mr. Wasser says his laboratory has developed a genetic test for ivory to track the elephant species of origin. He says it could become an important tool for enforcing their protection.