DNA Tests Show African Elephants Are Two Species
for National Geographic News
|August 24, 2001|
Genetic fingerprinting shows that Africa's forest and savanna elephants
are as different from one another as lions and tigers and should be
considered as two genetically distinct species, an international group
of researchers reports.
Up until now, elephants have been divided into two speciesAsian and African. However, there has been considerable debate among experts as to whether the differences between Africa's forest and savanna elephants were significant enough to identify them as separate species. The DNA evidence, reported in the August 24 issue of the journal Science, provides a definitive answer to the long-debated controversy.
The finding has implications for both international law and conservation strategies.
If there are two species, there are both fewer elephants in each population and they're more endangered than previously assumed, according to Nicholas Georgiadis, a biologist at the Mpala Research Center in Kenya and co-author of the study.
Seventy years ago there were between three million to five million elephants in Africa. Today there are around 500,000 elephants in Africa. Forest elephants comprise around one-third of that number, living in the equatorial forests of central and western Africa. The savanna or bush elephant is found throughout the grassy plains and bushland of the continent.
Forest elephants are smaller and have straighter and thinner tusks, rounded ears, and a distinct skull shape.
The social structure of the two species also differs. The family units of savanna elephants typically contain about ten individuals. Sometimes several families join to form a clan with up to 70 members, led by a large female. Forest elephants live in much smaller groups.
The differences between the two have long been noted, says F.V. "Loki" Osborn, an elephant researcher based in Zimbabwe.
Raphael Ben-Shahar, an elephant expert at Oxford University, says, "Up until DNA fingerprinting tests, species were defined on the basis of morphological and anatomical differences." Using the old classification yardsticks, the forest elephant was merely a subspecies of the savanna elephant. However, there was widespread disagreement among taxonomists as to whether the differences between the two elephant types were significant enough to denote separate species, he says.
The DNA evidence should put the controversy to rest.
"The impact on management strategies if there are two elephant species in Africa is huge," says Ben-Shahar. "Now we will have two species that are less numerous than was thought before."
Being killed for their ivory and loss of habitat due to encroachment by humans are threats faced by both African species. However, recognition of their genetic distinctiveness will allow wildlife managers to fine-tune conservation strategies to best protect each species. Forest elephants are more threatened by logging, for instance, whereas agricultural expansion poses a huge threat to the elephants of the savanna.
In addition, forest elephant populations are smaller, and their ivory is highly prized for its hardness and pinkish color. "The difficulty in detecting poaching in the rain forest may put the forest elephant more at risk," says Osborn.
On the other hand, the elephants of the savanna face more friction with humans because they live where people prefer to live, unlike the forest elephant, says Ben-Shahar. But their accessibility may garner more of the conservation dollars.
"It [the savanna elephant] is the more appealing of the two species for tourists because it is bigger and easily found. Would you pay much to see a reclusive elephant shadow in the jungle?" asks Ben-Shahar.
Recognition of the forest elephant as a separate species also has legal implications. The African elephant, Loxodonta africana, is listed as endangered under the Convention on International Trade of Endangered Species (CITES, pronounced like nighties). There is some concern that under current treaty regulations, recognition of a second species could open a loophole that would allow poachers to exploit the ban on ivory trade.
The IUCN Species Survival Commission African Elephant Specialist Group does not plan to address the two-species issue until early next year, according to Leo Niskanen, program officer for the group.
Funding for the study was provided by the National Geographic Society, European Union, National Science Foundation, National Institutes of Health, and U.S. Fish and Wildlife Service.
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