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Conservation biologists Samuel Wasser (left) and
Benezeth Mutayoba remove a piece of elephant tusk for DNA
extraction. Photo by Wendy
Schackwitz. |
Despite a long-standing
international ban on ivory trade, African elephants continue to be
killed in large numbers for their prized tusks. But a team headed by
UW biologist Sam Wasser has devised a new means of determining the
geographic origin of ivory, which could prove a potent tool in
slowing elephant poaching and the illegal ivory trade.
It is
relatively easy to monitor elephant populations with flights over
the open savannas of eastern, central, and southern Africa, but much
harder to do the same in the dense forests of central and western
Africa. Those forests are where elephants are currently being
slaughtered wholesale, says Wasser, who holds the UW’s endowed chair
of conservation biology and is director of the Center for Conservation
Biology.
“My colleagues working in the forests are
saying, ‘There are no elephants left here,’” he says. “That’s the
problem—in the forest you don’t notice the change in population
until it’s so dramatic that it’s almost too late to do anything
about it.”
The African elephant population plummeted by 60
percent—from 1.3 million to just 500,000—between 1979 and 1987,
largely because of ivory poachers. An international agreement
banning ivory trade was enacted in 1989, but still three of the
largest ivory seizures have occurred since 2002.
In June
2002, authorities in Singapore seized a shipment of about 6.5 metric
tons of ivory bound for the Far East. The shipment included 532
whole tusks, many more than six feet long, and 41,000 small carved
ivory cylinders about the size of hanko stamps, used for document
signatures. The cylinders alone were worth more than $6 million.
The new methods
developed by Wasser’s team are being used to show generally where
such ivory came from, alerting authorities to specific areas where
added enforcement is needed to curb poaching.
Wasser and his
colleagues extracted DNA from elephant droppings and skin biopsy
samples collected from numerous locations in 16 African nations.
They used that information to build a DNA-based reference map to
assign tusk origin. They noted genetic differences in populations
from one location to another, and used a statistical method to
extrapolate genetic signatures to fill in gaps between sampled
populations.
Matthew Stephens, UW associate professor of
statistics, developed a model allowing the researchers to build
genetic profiles for elephant populations from which they do not
have genetic samples. The model is weighted toward genetic
information obtained from populations nearest those for which
information is unavailable.
The method allows a DNA sample
to be assigned to a fairly specific location, with a relatively high
confidence that the assignment is correct. The study indicated that
50 percent of the samples tested were accurately located within 300
miles and 80 percent were accurate to within less than 600 miles.
Accuracy was much greater among forest populations, which are more
clearly defined because of terrain.
The new method allows
for speedy determination of where a particular ivory sample came
from, Wasser explains. That is important because there is
mounting pressure to lift the 1989 ivory trade ban enacted under
the Convention on International Trade in Endangered Species. But
many experts believe any legalization of ivory trade will only
increase poaching. The new sampling method can help determine
quickly whether that is true in time for exemptions to be altered
before elephant populations suffer catastrophic damage.
Two
years ago, five African nations sought, and three received, an
exemption from the ban so that they could conduct one-time ivory
sales. Now numerous other countries are considering seeking
exemptions, and some hope to obtain permanent exemptions.
“Once the door is cracked open, they try to force it open
all the way,” says Wasser, who notes that a number of countries have
kept ivory stockpiles since the 1989 ban. The small central-African
nation of Burundi has a stockpile of 80 tons despite the fact that
it had only one elephant at the time of the ban. Some observers
believe ivory has been sold from that stockpile and replenished from
poached ivory. “This method could detect such restocking in the
future,” Wasser says.
The research was supported by the U.S.
Fish and Wildlife Service, the Gordon and Betty Moore Foundation,
the Bosack Kruger Charitable Trust, the National
Institutes of
Health, the International Elephant Foundation and the Woodland Park
Zoo in Seattle. The entire ivory seizure investigation is being
funded by the International Fund for Animal Welfare.
[Winter-Spring
2005 - Table of Contents]
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