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Abstract |
If, in a mix-up at a costume shop, a couple were issued the front half of a zebra suit and the back half of a horse, it could be considered a quagga disguise. But if the masqueraders were pressed as to whether they were more horse or more zebra, the latest biochemical research advises them to insist on zebra.
The quagga, a South African animal extinct for more than 100 years, has been a source of confusion among taxonomists. Some contend, on the basis of the quagga skins preserved in museums, that this front-striped animal is a zebra, either a fourth zebra species or a variant of the Plains zebra, whose hindquarter stripes are dim. But others have argued that the quagga's teeth and skeleton indicate that its nearest relative is the true horse.
Biochemists joined the fray last year when muscle tissue was obtained from a salt-preserved quagga pelt in a West German museum. The tissue yielded both proteins and genes that could be analyzed (SN:6/9/84, p. 356).
Now the analysis has yielded some results. According to “remarkably concordant” findings on the proteins and on the genes, the quagga was a subspecies of the Plains zebra, says Jerold M. Lowenstein of the University of California at San Francisco. He looked at the binding between a sample of quagga proteins and mixtures of antibodies that bind to blood-serum proteins of each of the extant Equus species. The quagga sample bound more of the antibodies against Plains zebra serum than against the other species. Lowenstein calculates that the quagga relationship with the Plains zebra is six times closer than its relationship with the two other zebra species.
“We had to use special techniques to show the difference,” Lowenstein told SCIENCE NEWS. “There is 99 percent identity on the protein level. All the [Equus] species diverged within the past 5 million years, which is only yesterday in evolutionary terms.”
The quagga-Plains zebra relationship is further supported by the analysis of quagga mitochondrial genes performed by Russell Higuchi and Allan Wilson at the University of California at Berkeley. They find seven times as great a difference between quagga and Mountain zebra DNA as they do between quagga and Plains zebra DNA.
“Stripes, the molecules tell us, do make a zebra,” Lowenstein concludes in the July 18 NEW SCIENTIST, “and the half-striped quagga was a Plains zebra.” |
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