Cutting edge

January 28, 2000

'The programme is too short to generate new mutations.

Will the result be a genuine quagga or merely a fraudulent lookalike?' The quagga, extinct since 1883, may soon be roaming the plains of South Africa again thanks to a selective breeding programme On the lower slopes of the Devil's Peak, a mountain looming over Cape Town, lies Rhodes estate, a pleasant pasture in which the keen eye can discern what appears to be a group of zebra grazing contentedly on the grass. There are three extant species of zebra, plains zebra, mountain zebra and Grevy's zebra. Those on Rhodes estate are plains zebra, but a closer look reveals that they differ from typical plains zebra in that several have a marked reduction in the normal striped pattern over the latter half of the body and legs, and others have a darker brown background colour than would be considered normal.

These animals are part of a programme designed to attempt to reintroduce the "extinct" quagga into its former range in the western Cape region of South Africa. The last true quagga died in 1883 in Amsterdam zoo, the original herds having been exterminated by early colonisers.

The quagga pelage was zebra stripes on the head, neck and forepart of the body, while the latter part and legs were a uniform dark brown. The plains zebra is variable in its markings and among those living on the borders of the original quagga areas there are animals with significantly fewer stripes and some that are darker than usual. Two decades ago there was an idea to try to rebreed the quagga from such individuals.

A major problem prevented such an attempt at first since many authorities considered the quagga to be a separate species of Equid altogether. If this were correct it would be inappropriate to attempt such a programme starting with what would then be a different species of zebra. Even if the attempt was successful, the result would be no more than a quagga lookalike with no real relationship to the original article.

However, this problem was resolved by Russell Higuchi at the University of California, Berkeley in 1984, who managed to clone and sequence two segments of DNA from a piece of preserved quagga tissue and show that the sequences were effectively identical to those of plains zebra. This made a selective breeding approach more justifiable.

It can now be proposed that if the genes characterising the quagga, or at least the genes characterising the pelage characteristics on which the classification is based, can be brought together by selective breeding to produce the classic quagga phenotype, then there is justification for claiming that the quagga has been retrieved (we avoid the word "re-

created", which would convey the impression that we were making something new).

The programme is estimated to take about four generations. It is too short to generate new mutations, and exploits only those variables present in the living population. Will the result be a genuine quagga or merely a fraudulent lookalike? This creates an interesting debate among academic zoologists and conservationists, and centres on the criteria used in the original classification, and whether retrieval of these characters alone is sufficient for application of the term "quagga" to be acceptable. Some argue there may have been other features unique to the quagga that we are neglecting, but since these can never be determined, are such arguments relevant?

The results? We are now just into the third generation, and the results should speak for themselves. Come to Cape Town and see.

Eric Harley is an expert in genetic and molecular aspects of conservation at the department of chemical pathology, University of Cape Town, South Africa.

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