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Genetic tests suggest that African elephants who live in the forest are not the same as those who live in grasslands.
©Associated Press
© St. Petersburg Times, published August 24, 2001
WASHINGTON -- They live on the same continent and have big ears, trunks and tusks, but the forest and grassland groups of African elephants are two different species, a new study says.
The genetic dissimilarity between the forest and the savanna elephants "is as great as between lions and tigers and jaguars and snow leopards and all the big cats," said Stephen O'Brien, head of a genetic research laboratory at the National Cancer Institute.
O'Brien is lead author of the study appearing today in the journal Science. He and his co-authors analyzed genetic specimens collected from 195 African elephants and seven Asian elephants and found clear evidence of a "species level" genetic difference between the African types.
The samples were collected over eight years using darts fired into animals living in 21 widely separated groups in Africa. The darts punched and held a small skin sample from the animals, and then dropped to the ground so researchers could retrieve them.
The technique was developed to enable researchers to trace the origins of illegal ivory.
A researcher in Africa, Nicholas Georgiadis of the Mpala Research Center in Kenya, directed the collection. The study was conducted by O'Brien, Jill Pecon-Slattery and Alfred Roca at the National Cancer Institute, one of the National Institutes of Health.
O'Brien said the forest elephant is shy and seldom seen, but naturalists who have studied them have long noted their differences.
The savanna elephant, known to scientists as Loxodonta africana, has large ears with ragged edges and curving tusks. It ranges widely in the grassland and bush country of east-central and southern Africa. It is the elephant most commonly seen in zoos and by tourists visiting Africa. The largest concentrations are in Botswana, Zimbabwe, Zambia, South African, Tanzania and Kenya.
The African forest elephant, Loxodonta cyclotis, is slightly smaller and has rounded ears. Its tusks are straighter and longer and the ivory has a slightly pink hue, making it highly prized. It lives in dense woods in the Democratic Republic of Congo, the Central African Republic and Cameroon. Because of its remote and inaccessible habitat, it is less commonly seen. The only one in captivity is in a Paris zoo.
The Asian elephant, known as Elephas maximus, has much smaller ears and is widely used as a domestic beast of burden in Asia and is uncommon in the wild.
The difference between the African elephants is about 58 percent of the genetic difference between the African and Asian elephants, O'Brien said.
Something, perhaps some physical barrier, split the African elephants into two groups thousands of years ago, he said.
"We don't know what the barriers were between these two, but their habitats are clearly different and they have been isolated for a long enough time for speciation (evolution into different species) to take place," O'Brien said.
This led to "reproductive isolation," the hallmark for the concept of biological species, he said.
"When they did come into contact, they avoided breeding with each other," O'Brien said. Out of 21 groups genetically analyzed, only one showed evidence of crossbreeding, he said, and "that probably happened up to about 100 generations ago."
O'Brien estimated there are about 350,000 savanna elephants in Africa and about 150,000 forest elephants. Just 20 years ago, the population of African elephants was more than 1.5-million.
Samuel Wasser, a conservation biologist at the University of Washington, said he and his colleagues have conducted an even more extensive genetic survey of the elephant, and they agree that the African animals are of distinct species.
The forest elephant is entering a new phase of poaching danger, Wasser said, because logging and road building have penetrated its dense jungle home.