In a laboratory at Columbia University, biologists are studying the DNA of black lion tamarin monkeys, using the latest genetics technology to accomplish a seemingly old-fashioned goal: matchmaking.
It is computerized dating with a mission. There are only some 1,200 black lion tamarin monkeys, all of them in the Atlantic forest of eastern Brazil. Moreover, because of human development the monkeys are scattered among nine different patches, with some groups having only a few dozen members.
Animals that would normally roam to find a mate are limited to a small selection of candidates, most of whom are close relatives.
”The loss of genetic diversity is one of the biggest causes of extinction,” explains Don Melnick, a professor of biology and anthropology at Columbia and the head of CERC, the Center for Environmental Research and Conservation. When the genetic makeup of a small population of animals becomes too homogeneous, the entire group may be wiped out by a single epidemic.
Furthermore, potentially lethal genetic defects that are normally recessive in a larger population begin cropping up with increased frequency as animals mate with close relatives, creating a negative spiral from which it may not recover.
Mr. Melnick’s approach is one of the many strategies of an important new field, conservation genetics, which uses genetic information in an effort to preserve endangered species. During an era in which the large, wild spaces where many species evolved are being broken up by human development into smaller and smaller fragments, it is becoming an increasingly urgent remedy.
”In conservation, we’ve learned that it’s not enough to protect an area in order to save a species,” says Mr. Melnick. ”If a population has lost its genetic diversity, you can build a wall around its habitat and the species will still die off.”
The problem is serious even for species whose absolute numbers are reasonably good. There are, for example, some 55,000 Asian elephants — a viable number for long-term survival — but they are divided up into hundreds of groups in dozens of different Asian countries, severely reducing their genetic diversity. ”Realistically, since we are not going to get back a lot of forest, we have to fool nature by creating the same genetic diversity as if the animals were moving around in one large, continuous space,” says Mr. Melnick.
But the uses of genetic information are hardly limited to the mating of animals. A few years ago, scientists at the American Museum of Natural History started something called the ”caviar project”: they began testing various kinds of caviar for sale in New York to see whether the roe came from endangered species of sturgeon, which are supposed to be off limits to commercial fishing. Taking samples from premium food stores, they found that about 25 percent of the caviar was mislabeled. Importers appeared to be either passing off less exalted kinds of fish eggs as fancy beluga caviar or selling the eggs of species that are supposed to be protected. The United States Fish and Wildlife Service then adopted its own method of genetic fingerprinting of caviar and began banning shipments. The method is not universally accepted by scientists, however, and this has generated at least one lawsuit from caviar suppliers who insist they have been unfairly damaged.
Now, genetic gumshoes in New York and other large cities are scouring apothecary shops in Chinatown to test medicinal powders that may contain rhino horns, seal penises, or bear gall bladder from endangered species whose body parts are greatly prized by traditional oriental medicine.
In a similar fashion, researchers from the Center for Conservation and Evolutionary Genetics at Harvard University make an annual pilgrimage to the sushi markets of Tokyo to see whether the Japanese are selling the meat of whales that are supposed to be protected by international whaling conventions. Since it is illegal to take whale meat or whale DNA out of Japan, the biologists must discreetly set up a small genetic laboratory in a hotel room.
To their surprise, they found all sorts of things — dolphin, porpoise and even goat meat — being sold as highly expensive whale flesh at $50 to $100 a pound. About 30 percent of the whale for sale was from protected species, says Steve Palumbi, the director of the Harvard Center and a professor of evolutionary biology. In the six years since the program started, he said, that has dropped to about 5 percent.
These sorts of tests have been made possible by a series of technological breakthroughs of the last 10 or 15 years.
Unquestionably, the biggest single innovation is a procedure called polymerase chain reaction, or P.C.R. It was devised in the early 1980’s by Kary Mullis, who was awarded the Nobel Prize in Chemistry in 1993 for his work.
Mr. Mullis figured out how to replicate large amounts of DNA quickly from tiny amounts of organic material, using an enzyme present in a microorganism that lives in the hot geysers of Yellowstone National Park. Mr. Mullis’s P.C.R. machine allowed scientists to take a tiny fragment of DNA and produce enough genetic material for a detailed study of a species or an individual. It is the basis of the genetic profiling in everything from the O. J. Simpson murder trial to the human genome project.
”For molecular biologists, history is divided into the world before P.C.R. and the world after P.C.R.,” says George Amato, the director of the Joint Conservation Genetics Program, sponsored by the Wildlife Conservation Society and the American Natural History Museum.
By the early 1990’s P.C.R. machines were cheap enough for use in most major laboratories, and by the mid-1990’s they were portable enough to use in a Tokyo hotel room.
The other big breakthrough was the invention of a machine known as the ”automated DNA sequencer.” The machine combines laser and computer technology to read the precise sequence of thousands of nucleotides in a strand of DNA.
”What people used to do for their entire Ph.D. dissertation over two years, I can have an undergraduate do in a week,” says Mr. Melnick at Columbia. These DNA sequences can then be used to create the genetic trees of an entire species. In the CERC laboratory at Columbia, one of Mr. Melnick’s researchers has assembled the entire evolutionary history of the Macaque monkeys of Southeastern Asia on his computer.
The breakthroughs in P.C.R. machines and automated genetic sequencing has opened up the field of what is known in common parlance as ”Jurassic Park” research: reconstructing the DNA of long dead or even extinct species. Researchers at the Natural History Museum in Sydney, Australia, for example, are attempting to revive the extinct Tasmanian tiger from the DNA of a tiger cub that has been preserved in a jar since the 19th century.
Although few scientists expect this to work anytime soon, others are already using DNA from museum specimens to help conserve endangered species. Howard Rosenbaum at the Museum of Natural History in New York, for example, has compared the DNA of living examples of the Atlantic right whale, a nearly extinct species of whale that lives off the coast of the northeastern United States, and the DNA of whales that were caught and hunted hundreds of years ago. Since the whales were prized as trophies and museum objects as far back as the 17th century, there is a rich database of genetic material to work from.
By studying the changes in the DNA over time, the scientists are hoping to compare the genetic diversity within the species at a time when there were millions of the whales to the diversity today, when there are only about 300 left. Although the study is not complete, preliminary research indicates that the genetic diversity of the species dropped significantly until the early 20th century but that it has remained fairly stable since. ”There was a moratorium right in the middle of the big whale slaughter in the 1930’s,” says Rob De Salle of the natural history museum. ”The fact that the genetic variablity appears to have been preserved since that time tells us that whaling moratoriums and conservation efforts are good.”
Although the leading laboratories for genetic conservation are concentrated in the United States, Canada and Europe, a large number of countries are becoming aware of the conservation potential of genetics. Mr. Palumbi of Harvard is working with the government of Indonesia, for example, which is seeking to set up between 30 and 40 marine parks, areas that are designed to protect marine wildlife.
Mr. Palumbi is trying to create a genetic map of various underwater populations so that the Indonesian government can make intelligent decisions about which are more or less important to preserve. ”Sometimes the boundaries in the sea are difficult to see,” Mr. Palumbi says. ”Once we have that genetic map, we can match it with the park map.”
Similarly, the government of Venezuela contacted the Wildlife Conservation Society after it had confiscated some rare parrot chicks from poachers who were trying to export them for sale. Officials wanted to know whether they should release the parrots into the population of a bird sanctuary on Marguerite Island. ”We determined that they did not belong to a separate subspecies, and I thought there were very compelling reasons to add greater diversity to the protected birds in the reserve,” says Mr. Amato of the conservation society.
The hands-on application of genetics to conservation has helped create a new hybrid type of scientist: it brings field biologists into the laboratory and sends molecular biologists out into the field. Mr. Amato was trained at Yale in evolutionary biology but recently found himself on a boat off the coast of Madagascar shooting a crossbow at whales to get small amounts of DNA.
”I was talking to a colleague of mine about what we should call ourselves,” says Mr. Amato. He did his Ph.D in genetics, while his colleague, a wildlife biologist, has worked mostly out in the field. ”I’m a wildlife biologist, too. He looks at rhinos through binoculars, and I look at these molecules of the DNA. But I still see a rhino. We are interested in the same things: Why is life the way it is? Why do the animals do what they do and how do they do it?”
– December 12, 2000
As published in The New York Times