Biotech the Latest Defense in Animal-Extinction Fight
National Geographic Today
|January 16, 2003|
Later this year, reproductive biologist Betsy Dresser will check some
rather extraordinary luggage on a flight from New Orleans to Kenya: Two
thermoses containing about 50 bongo embryos, cryogenically frozen at
385° F (232° C) in liquid nitrogen. Hopefully,
these embryos will develop into healthy calves that will repopulate
bongo herdsendangered antelope that are rapidly disappearing from
their African range.
Upon arrival at the 10,000 acre (4,047 hectare) Mt. Kenya Game Ranch, Dresser and her team will implant these bongo embryos into about 25 surrogate eland mothers that have received three weeks of hormone injectionslike those given women preparing for in-vitro fertilization (IVF). After a few weeks, the eland will be pregnancy testedand the researchers will wait out the 11-month incubation period.
Dresser, director of the Audubon Institute Center for Research of Endangered Species (AICRES) in New Orleans, is a pioneer in "cross-species embryo transfer," an experimental method of breeding endangered species with the help of their more-plentifulor domesticrelatives. "Nobody has ever done this (embryo transfer) in the wild before," she said.
Conservation's New Front
As Earth's wild places vanish and the numbers of animals facing extinction rises, the fight to save dwindling wildlife is expanding on a new front: in the laboratory. Researchers are adapting techniques like artificial insemination, cloning, in vitro fertilization and inter-species embryo transfer for use in threatened species.
Dresser has successfully "incubated" bongo calves in eland mothers before in captivity, with fresh, not frozen, embryos. This current project follows her 20 years of reproductive work with endangered speciesincluding the birth of the first "test-tube" gorilla in 1995 when Dresser was with the Cincinnati Zoo.
"There is a rapidly growing interest in assisted reproduction technologies in conservation," said Oliver Ryder, a geneticist at the San Diego Zoo's Center for Reproduction of Endangered Species (CRES).
For some at-risk species, biotech conservation represents the last chance to preserve precious genetic diversity, a benchmark of species health and well-being. Toward this end, zoos have become genetic repositories for cryogenically frozen eggs, embryos, sperm and tissue.
The Frozen Zoo
The first so-called "frozen zoo" was created in 1975 by Kurt Benirschke, a visionary physician who switched from his human practice to work with endangered species at the San Diego Zoo, studying gene pools and genetic diseases made prevalent by inbreeding.
Today, in zoos around the world, these deep-freeze tanks act as a high-tech Ark, housing cells from the planet's most endangered animals, including chimps, cheetahs, pandas, California condors and hundreds more.
As a result, long-dead animals are now becoming parents from the grave, with their precious DNA still circulating in the gene pool.
"The real goal is the management of the eroding gene pools of endangered species," says Ryder.
Researchers are mapping familial relationships between animals and breeding both captive and wild animals through "arranged marriages" to maximize genetic vigor.
There are species that desperately need help from captive situationssuch as the Sumatran rhino. "We can't save it in the wild," said Alan Rabinowitz, director of Science and Exploration at the Bronx-based Wildlife Conservation Society (WCS). "We just cannot keep up with hunters following a single animal for months, going after its horn. There are species like that where captive technologies and breeding is crucial."
But captive breeding is not always easy. Many animals are disoriented by living in the wrong climate or social system, or being squeezed into small "habitats" in the presence of humans.
Scientists and keepers try to help animals breed naturally. But often, researchers do not even know how normal mating takes place. "We're missing a lot of the basic information on the biology of most animals," said George Amato, Director of the Conservation Genetics Program at WCS.
So zoos and conservation parks across the US and abroad are developing costly, hi-tech reproductive research programs. By combining assisted breeding techniques with wildlife management and reintroduction of captive-bred animals, they hope to boost wild populations and genetic diversity.
There are a few early success stories. This year, researchers from the Smithsonian National Zoo produced their hundredth black-footed ferret through artificial insemination, animals that were on the precipice of extinction. They are being returned to their former habitat in the West.
"The black-footed ferret and the California condor are two species that would be extinct now without these programs," said Amato.
At AICRES, sand hill cranes are produced through artificial insemination, incubated, and raised by researchers costumed as cranes to prevent human imprinting. They are reintroducing 20 of the birds each year to the Mississippi Sand Hill Crane Refuge in Pascagoula. The endangered flock now numbers over 100.
Some plans are more elaborate. Steven Monfort, a veterinarian at the Smithsonian National Zoological Park's Conservation & Research Center in Front Royal, Va., is conducting habitat surveys in Niger and Chad to find a place to reintroduce a "world herd" of scimitar-horned oryx, a type of antelope.
Zoos from around the world will contribute either female oryxes or oryx sperm to create the widest-possible genetic mix. "Without this type of multi-institutional cooperation, captive populations can't play much of a role in conservation of wild populations," said Monfort.
Cloning Comes to Conservation
Cloning, too, has come to conservation. CRES is collaborating with Advanced Cell Technology in Worcester, Mass. to clone endangered banteng, a species of Asian cattle. Eleven milk cows on an Iowa farm are currently pregnant with banteng babies.
Dresser's team is fine-tuning the cloning of small cats like the African wildcat, as well as the largest: tigers. They are also working with banteng and antelope species.
China is developing a program to clone pandasusing rabbits as surrogate mothers for panda cubs, which are only a few inches long at birth.
Critics argue that expensive biotech programs siphon money away from the real goal of wildlife protection in the animals' native habitats. Without proper conservation, suitable habitat may disappear, leaving nowhere to put these animals conceived in Petri dishes.
"As a whole, people have got to look at biotech as a backup system, not as the driving force in conservation," said Rabinowitz.
But many animals hover on the brink of extinction in the wild despite conservation efforts. Protecting these species is such a massive, complex problem that many agree it is critical to throw as many strategies at it as possible.
"I don't believe one thing will save these species," said Dresser. "This technology will help form a safety net, but habitat conservation is critical."
"I think the future will thank us for what we can save," said Ryder.
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