Elephants should be hard to miss. But scientists have apparently overlooked an entire species: In the 24 August issue of Science , a team of researchers shows that forest- and savanna-dwelling elephants, currently lumped together in a single species called Loxodonta africana, each merits its own species name.
For over a century, scientists have argued about the distinctiveness of forest elephants, shy creatures that are difficult to spot in their thick forest habitat. But those who have seen them point to unique features: Forest elephants are not only smaller than those on the savanna, but they also have straighter, thinner tusks and round, as opposed to pointed, ears. "If you see a forest elephant for the first time, you think, 'Wow, what is that?,'" says team member Nicholas Georgiadis, a biologist at the Mpala Research Center in Nanyuki, Kenya. Yet most biologists had assumed that the elephants readily mix on the edges of forests, and forest elephants were usually designated as a subspecies, Loxodonta africana cyclotis.
Over 8 years, Georgiadis used darts to collect tissue samples from 195 free-ranging elephants in 21 populations. He then teamed up with Alfred Roca and other researchers at the National Cancer Institute in Frederick, Maryland, who pegged the genetic distance between forest and savanna samples as more than half the distance between Asian and African elephants--long recognized as distinct genera. Only one population showed the type of genetic mixing that could come from interbreeding, and that apparently happened several generations ago, suggesting that crossbreeding is rare. The team now proposes two species names: Loxodonta africana for the savanna elephants and Loxodonta cyclotis for the forest dwellers.
"The morphological evidence has been very, very strong," says conservation biologist Samuel Wasser of the University of Washington, Seattle. "When you see the genetic data, it seems almost a no-brainer." The new genetic evidence has implications for conservation, says Georgiadis. Instead of assuming that there are 500,000 elephants in Africa, "there are many fewer than that of each kind, and they're both much more endangered than we presumed," he says. Researchers estimate up to one-third of African elephants live in forests.