|CERES No. 135 (FAO Ceres, 1992, 50 p.)|
When is a quagga an Equus quagga quagga and when is it a mere Equus quagga in quagga's clothing? Quite a question, say geneticists, who can't agree yet among themselves whether a foal born recently in South Africa's Vrolijkheid Breeding Centre is only a slightly off-colored plains zebra or the true resurrection of a supposedly extinct species.
The answer could have important implications for those interested in preserving both rare domestic animal breeds and endangered wild species.
The original quagga was a partially striped, cream-and-brown, horse-like animal that roamed the plateaus of southern Africa until roughly a century ago, when it was hunted to extinction. Ceasing to exist did little, however, to dampen controversy among zoologists over its proper classification. Some believed it a species in its own right - E. quagga quagga others thought it a cousin of the mountain zebra (E. zehra), and still others were convinced it was a sub-species, perhaps even a mere color-phase, of the plains zebra (E. quagga).
Zebras and horses, as well as quaggas, share certain similarities, due to the persistence of primitive characteristics inherited from a common ancestor that lived 3.3 million years ago. But each creature also has its own unique traits. Thus, quaggas sported their own colors and didn't live among zebras, keeping instead to their own territory south of the River Orange. The last living quagga, a mare, died on 12 August 1883 in Amsterdam's Zoo Artis. Today, only stuffed specimens, such as that kept in the Amsterdam Zoo Museum, are extant. Geneticists at the Vrolijkheid Breeding Centre, however, are unwilling to accept history's verdict of final doom. For several years they've carried out experiments aimed at "retrieving" the quagga via selective breeding of plains zebras for quagga-like traits. In 1988 eight foals were born more or less resembling E. quagga. The experiments continued until this year, when scientists announced that their latest foal was, externally at least, a genuine quagga look-alike.
Quest for a quagga
If the animal is a real quagga, it would confirm the results of work by American geneticist Russel Higuchi, of the University of California at Berkeley. Prof. Higuchi earlier cloned fragments of mitochondrial DNA from preserved samples of quagga tissue and found similarities with the DNA of the plains zebra. Other work based on the interpretation of skull and tooth characteristics has also established that the quagga and plains zebra were "sister" species. Differences between the quagga DNA sequences and mountain zebra DNA, however, indicate a diversity between those species.
Has the quagga been brought back from oblivion?
Some geneticists think not, and make no bones about it. Peter J.H. van Bree, curator of the Department of Mammals at the Zoological Museum of Amsterdam, is adamant: "It's as if we managed to reproduce a double of Napoleon, but we could never bring the emperor back.
"It's always possible to breed back the external aspect of a certain form which occurred within a species. For instance, between the two world wars the Heck brothers (one a former director of the Munich Zoo), by selective breeding of domesticated cows, managed to get animals which looked like aurochs, the extinct ancestor of modern cattle. We now know that these animals were not aurochs, but only look like aurochs.
"They are doing the same now in South Africa with plains zebras. They are creating animals which look like quaggas, but which never will be true quaggas. These experiments are interesting for the public, but scientifically speaking of little value. The sub-species E. quagga quagga has died out and cannot be replaced by plains zebras".
Obviously, the last word on the quagga has yet to be heard.