Carnivorous Nights_ On the Trail of the Tasmanian Tiger - Margaret Mittelbach [16]
The first such trans-species birth was in 2001 when a cloned guar— an extremely rare species of wild ox that lives in Southeast Asia— was brought to term inside a cow named Bessie. This experiment was followed up in 2003 when a cloned Javanese banteng, a rare species of wild cattle, was born on an Iowa farm. The banteng's “mother” was a beef cow. In China, scientists are currently working to produce embryonic clones of giant pandas that could be “mothered” by black bears.
This is how the tiger clone would be created. If cloning scientists are able to reconstitute the thylacine's genome, they will need to pick a species to be the tiger's surrogate mother, an Eve for a new race of thylacines. This animal will have to be as closely related to the tiger as possi-ble—which presents a bit of a problem.
“The thylacine was the sole remaining representative of its family,” Don said. As a species, the Tasmanian tiger diverged from its closest cousin 25 million years ago. Of the sixty or so species of living marsupial carnivores—all of which are potential candidates—none look very much like the tiger. These species include such creatures as the dusky antechinus, a mouse-sized marsupial with a giant-sized sex life (its copulation is described as “violent” and the males all die of stressrelated disease within three weeks of mating); the spotted-tailed quoll, a forest predator that looks like a cross between a cat and a weasel; and the Tasmanian devil, a black-furred scavenger with powerful, bonecrunching jaws.
“I think it would come down to the devil really,” said Karen. “The devil is the largest of the carnivorous marsupials.”
Although only one third the size of the thylacine, the Tasmanian devil is a fierce beast. And like the thylacine and all marsupials, the devil gives birth to tiny incompletely developed young, which it suckles in a protective pouch.
To create this devil of a tiger, the cloning scientists would take an unfertilized egg from a female Tasmanian devil, remove all the devil DNA from inside, and then micro-inject the tiger's DNA into the egg. Then they would zap the egg with an electrical pulse. The egg and DNA would fuse, and cell division would begin. Shortly thereafter, they would implant the resulting microscopic embryo into the devil's womb and a few weeks later a tiny tiger would be born.
Alexis, who had been quiet up to this point, suddenly perked up. “So are you saying the tiger would be part devil?” he asked. His eyes gleamed as if he were picturing what a thyla-devil would look like.
Don laughed, three short barks.
In fact, he said, they would have to drive the devil out. A tiny portion of the devil's genome would get into the tiger clone. “It would be less than a millionth devil,” Don said. “We would have to disable the mitochondria if we wanted it to be entirely thylacine.”
Karen was less concerned about the bedeviled eggs. “It might just be that they can survive with devil mitochondria,” she said.
When it came to the question of what would happen to the tiger after its birth, they were stumped. Hand it off to the vet? Marsupials aren't like placentals. The birth occurs when the young are blind, hairless, and in a state of very early development. These underdeveloped infants have to crawl on their own power to the safety of their mother's pouch, where they develop further over many months. How would a cloned tiger make it to the devil's pouch? Could it drink devil milk? Would pet food companies have to develop a baby tiger formula?
“I don't know. Perhaps it might be safer if they were attached and suckling,” Karen said hesitantly. Then again, there was the possibility that the devil stepmom might eat it. Some carnivorous marsupials, she pointed out, can give birth to supernumerary young. “They give birth to many more than they can actually carry. But I don't know of a documented case where carnivorous marsupials have cannibalized their own pouch young.