|In South Africa, the Quagga Project Breeds Success|
|Zebra breeding program creates offspring with traits of an extinct relative|
Edward R. Winstead
October 20, 2000
In January, a falling tree struck and killed the last bucardo mountain goat in northern Spain. The species was endangered for decades, and Spanish scientists anticipated its extinction. In the spring of 1999, local veterinarians captured the 13-year-old female and collected a sample of cells before releasing her with an electronic tracking device. American scientists have expressed interest in using the DNA to create a genetic clone of the animal.
Cloning the dead animal obviously will not restore the species. A clone of the last bucardo mountain goat would still be the lone member of a species with no potential mates. Despite its limited value in conservation, cloning is being tried on endangered species. A cow in Iowa is expected to give birth next month to a genetic clone of an ox-like animal that is endangered in Asiathe gaur. Scientists in India recently announced plans to clone the Indian cheetah, which was hunted to extinction in that country decades ago but exists elsewhere.
An extinct animal that will never be cloned is the quagga. This relative of the horse once roamed the central plains of Southern Africa by the thousands, but the quagga genome is gone. In the 1800s, European settlers shot all the quaggas in the wild. The quagga was seen as an unwanted grazing competitor to the farmers' livestock, as were all the other grass-eating wild animals. It was also killed for sport, meat and its exotic hide. The animal looked in the front half like a zebra and at the back like a horse: It had zebra stripes on the neck and shoulders and pale, brown hindquarters. The last quagga in captivitya mare at the Amsterdam Zoodied in 1883. Only years later did scientists realize the species was extinct.
The quagga is gone, but quagga genes may have survived. DNA studies in the 1980s suggested that the quagga is a cousin of the plains zebra, which today roams throughout much of Africa. Researchers compared DNA from a preserved quagga hide in a natural history museum to that of a plains zebra and found in each sample the same stretches of genetic code.
The experiment involved relatively small amounts of DNA, but the result was consistent with a theory that the quagga was a subspecies of the plains zebra rather than its own species. One of the main proponents of this theory is the South African taxidermist who retrieved the quagga DNA, Reinhold Rau. Rau believes that quagga genes are preserved in the genome of the plains zebra, and in 1987 he launched a project to try to 'rescue' those genes.
The goal of the Quagga Project is to create a population of plains zebras that resemble the quagga in appearance. Rau and a group of researchers and conservationists are selectively breeding plains zebras that have quagga-like traits, an approach that livestock and horse breeders have used for centuries. No zebra genomes are copied or altered.
"The quagga was a local form or subspecies within a species that still exists," says Rau, who is now 68 and until recently was head taxidermist at the South African Museum in Cape Town. "We are trying to retrieve the genes that are responsible for the brown color and the reduced striping of the quagga."
In 1969, after arriving in Cape Town, Rau painstakingly dismantled and remounted the quagga foal in the South African Museum. Rau found that techniques of nineteenth-century taxidermy, which would be considered sloppy today, had preserved connective tissue.
The following year, Rau toured European museums to examine and photograph 22 of the world's 23 quaggas (he did not visit the one in Russia). He eventually remounted five specimens, finding preserved tissue, bits of muscle and even blood vessels. "Restoring such a valuable specimen is risky business because the animal could easily be destroyed," he says.
Seeing and handling the hides persuaded him of the link between the quagga and the plains zebra. Coat patterns vary greatly among the museum specimens, and he knew that some plains zebras in different geographic regions differ in their striping and coloration. In general, striping tends to be reduced as one moves south. This seems to make evolutionary sense, because pale hindquarters in the plains of Southern Africa are camouflage against predators.
Rau tried to get a breeding project going in 1975, but no one shared his theory about quagga genes. Scientists he approached told him that the tissue was too old to reveal anything about quagga DNA. Then, in 1981, Oliver Ryder, of the Zoological Society of San Diego, became interested in the samples. Conventional wisdom of the day held that the quagga was a closer relative to the horse than the zebra. Ryder and colleagues analyzed the DNA and found the opposite: The quagga is likely to be a closer relative to the zebra than the horse.
The DNA samples were too small to say definitively how the quagga and plains zebra are related. Furthermore, the quagga DNA came from mitochondria, a structure in cells, rather than from the genome. Protein was also analyzed at that time. Examinations showed that the relationship between the quagga and the other plains zebras is closer than that between the two subspecies of the African wild ass.
"We are desperately waiting for the analysis of more DNA by Ann Oakenfull," says Rau. Oakenfull is a geneticist at the University of Cambridge, and she has quagga scrapings that were not used in the earlier studies. Although the quality of the DNA is questionable, she intends to compare it with that of several plains zebra populations.
"The relationship between the quagga and the plains zebra is still in dispute," says Oakenfull, who trained with Ryder. "We now have more information on the DNA of the plains zebra, so it makes sense to attempt more studies."
Oakenfull investigates the horse, and her laboratory recently published a paper describing techniques for mapping horse chromosomes. "For me, the quagga is an intellectual curiosity," she says. "We can't recreate the quagga. It's gone."
Rau agrees. "We would do the world a great disservice to suggest that extinction is any less serious than it ever was," he says. "When a species is extinct the entire gene pool is gone. That is final."
Basic questions about the quagga may never be answered. "We will never know how genetically similar the quagga is to the plains zebra because the entire genome of the quagga is not known," Rau says. "We are selectively breeding the plains zebras to concentrate the characteristics so that we at least have the appearance of the quagga."
Indeed, the Quagga Project is strictly about appearances. The physical traits of new foals are the only measure of the project's success. This has drawn criticism from conservation biologists who argue that the quagga was unique in many respects beyond its physical traits.
"The quagga had genes and attributes that were different from the plains zebra, even if we don't know what they were," says George Amato, director of conservation genetics at the Wildlife Conservation Society in New York. "So, strictly speaking in terms of evolution, if you were able to produce an animal that looks the same as the quagga, it is not the same."
Oliver Ryder serves as an advisor to the Quagga Project, but he agrees with Amato. "We can expect," he says, "that the quagga would have numbered in the millions and was a genetically diverse species. Re-breeding this animal can't establish the full extent of the genetic diversity." The project, he says, does not work toward the goals of conservation: "The purpose of conservation genetics is to give the future the robustness of genetic diversity minimally perturbed."
Nonetheless, the Quagga Project seems to be advancing toward its goal with relative speed. Rau had predicted that several decades of selective breeding would be required before zebra foals would be born with the physical traits of the quagga. "In 13 years," he says, "we've achieved more progress than anyone thought was possible."
On Valentine's Day 2000, a zebra filly named Tracy was born with only remnants of striping on her hocks. She is the daughter of Luke, and she will have as a likely mate Etienne, who was born on October 14, 1998. Both are second-generation offspring in a population that has grown in number from nine to more than 50.
The original nine Quagga Project zebras were selected and captured from some 2,500 plains zebras in Namibia's Etosha National Park in the spring of 1987. Each has reduced striping or brownish hindquarters. A special breeding camp was constructed for the zebras, and the first foal was born in December 1988. A total of 14 zebras were released into the Karoo National Park, the ancestral territory of the quagga. They have settled in extremely well, and eight foals have been born there since.
In June, the Quagga Project signed an agreement with South African National Parks that will facilitate the adoption and relocation of animals to Cape Town. The agreement changes the Quagga Project from a private initiative to an officially recognized and logistically supported project. Support for the project has until now come primarily from hunters. "The hunters of today are very conservation-minded," says Rau. "They are our main source of financial support. It's almost as if they feel guilty about what happened 150 years ago."
Rau has heard the rumors that the Quagga Project inspired the author Michael Crichton to write Jurassic Park. He doesn't know if they are true. But he points out that no one in his project is cloning the DNA of extinct creatures. "As some have observed," says Rau, "the Quagga Project is science fact and Jurassic Park is science fiction."
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