Health & Science Newsletter

August 17, 2014

Cryogenics, selective breeding help save animals facing extinction

Amani, an eye-catching cheetah, has genes that make her one of the most important individuals in her small community in northern Virginia. Biologists at the Smithsonian Conservation Biology Institute study her every move, hoping her cubs will help increase the thinning cheetah populations at zoos across the country.

She’s not just another girl with a pretty face living in Washington, D.C.’s outer exurbs.

Amani, an eye-catching cheetah feline, has a proud name that means aspiration and a strong family line that traces to Namibia and South Africa. Her rich genes make her one of the most important individuals in her small community just outside Front Royal. Unlike people who pay up to $2,000 for ancestral DNA tests, Amani got hers free, courtesy of biologists at the Smithsonian Conservation Biology Institute who study her every move, hoping her cubs will help increase the thinning cheetah populations at zoos across the country.

Nestled in the Blue Ridge Mountains near Shenandoah National Park, the 3,200-acre institute is at the forefront of an ambitious attempt by American zoos to save animals threatened with extinction by studying them relentlessly. As at zoos across the world, every animal at the institute and at the National Zoo in Washington is assigned a name that goes into a giant family album called a “stud book” that follows them from birth.

“We take data from every single animal in a population that’s being managed,” said Sarah Long, director of the Population Management Center at the Association of Zoos and Aquariums, which guides animal management at 220 accredited zoos.

Zoos are taking extraordinary steps to overcome three key challenges: sustaining their populations without allowing breeding between animals with similar genes; replacing animals without taking too many from the wild; and replenishing hundreds of species of threatened and endangered wild animals that are disappearing around the world.

More than 400 biologists and researchers volunteer for stud-book duty, laboriously pecking data into a computerized tome for every species. “They write down who the parents were, where they came from in the wild, tracking the pedigree, the family tree,” Long said. “We look at all the events in the animal’s life, if they’ve been transferred from another zoo, if they’ve given birth, if they’ve moved into an exhibit.

“We analyze the birthrate and death rate to predict how many offspring they’ll have in a given year. We need to plan for that and produce more births. We do the family tree to determine who should mate with whom to avoid inbreeding.”

Pandas, black-footed ferrets

It’s actually much deeper than that. Zookeepers not only encourage every animal from ferrets to rhinoceros to breed naturally, but they’re also in the middle of an all-out effort to cryogenically freeze and preserve semen, even taking samples from animals a few days after they’ve died, so that it can be resurrected in a way with the birth of offspring through insemination as much as 10 years later.

Case in point: The frozen semen of Jimmy, an Asian rhinoceros, was rushed from the Cincinnati Zoo and Botanical Garden to the Buffalo, N.Y., Zoo in a Volkswagen to inseminate Tashi, who gave birth nine years after the father’s death. It worked, to the amazement of biologists, because even though an animal’s cells don’t die at the instant they do, freezing semen and preserving living cells is a tricky business that has resulted in scores of failures.

One remarkable success is pandas. A study released this summer attributed a combination of artificial insemination and natural mating to “high levels of genetic diversity and low levels of inbreeding” among captive giant pandas. Pandas no longer have to be captured in the wild for breeding, according to the study, published in the online journal of Molecular Biology and Evolution.

The National Zoo has its own example, Bao Bao, a female panda cub conceived “as the result of a precisely-timed artificial insemination by scientists from the Conservation Biology Institute and China,” the zoo’s website said. The zoo is expected to celebrate her birth on Aug. 23.

The institute near Front Royal is studying and breeding 22 species, as small as the endangered American black-footed ferret – 800 of which have been bred through artificial insemination – and as big as the Mongolian Przewalski’s horse, which bears a striking resemblance to horses in ancient cave paintings.

“This species was extinct in the wild in the 1960s,” said their caretaker, Budhan Pukazhenthi, a research scientist. Scientists started breeding the few captive horses that remained in that decade. Now there are 1,600 globally, mostly from artificial insemination with frozen and thawed semen, and nearly a third have been reintroduced in the wild.

About 300 ferrets bred at the institute are now roaming the American plains, eating prairie dogs, their staple diet, and trying not to get eaten by coyotes. That’s nothing compared with the 100,000 that should be there, said Paul Marinari, the institute’s senior curator and stud-book keeper for the species.

Amani’s genes

Zoos in America haven’t always been this enlightened. When they needed animals to keep family members in their populations from inbreeding, risking some type of genetic mutation, they often simply grabbed them from the wild.

In the 1970s, when the new Endangered Species Act limited such captures, zoos in the United States increased their efforts to trade animals to keep sex out of the family.

That’s how Amani wound up at the National Zoo, where the population of cheetahs was thinning, nearly 30 years later. She was born at Wildlife Safari in Winston, Ore., the daughter of Bryden, imported to the United States from Namibia, and Missy, imported from South Africa, both carrying genes that had not been introduced at the Washington zoo.

Amani arrived in 2007 with her spotted honey-colored coat and big caramel cat eyes, and soon biologists were salivating over her potential to diversify the cheetah gene pool. Within two years, she was ushered to the institute nearly 100 miles west in the mountains where the breeding program is run.

Getting cheetahs to couple is often a nightmare, and so it was with Amani. Artificial insemination isn’t an option, because biologists haven’t figured out the ovarian cycle of females: Only one artificial insemination in Cincinnati has been successful in a long list of failures.

So cheetah biologist Adrienne Crosier undertook a painstaking process to mate Amani. Males that are kept far from pens holding females were brought close. Biologists know a female is in heat, ready to breed, when males smell her and bark in a chirplike stutter.

If barking happens, they’re brought face to face. If they like each other, it’s on. Often, they don’t. Amani rejected several males before finally mating and bearing a cub, Nick. A lone cub is a problem because cheetahs normally abandon single cubs, as they don’t feed enough for their mothers to keep producing milk.

Crosier thought Nick was doomed. In desperation, she took Nick from his inattentive mother and gave him to Zazi, a second mother that birthed a single cub at the same as Amani.

“I was nervous. It was a big risk,” Crosier said. Zazi might have killed a cub that wasn’t her own. Crosier slept in a cramped shed near Zazi’s pen to monitor her, and when that got old, slept in four-hour shifts at home between racing to the sanctuary.

“I think she knew right away he was different,” she said. “And you know, she picked up both, groomed them both, fed them both. She was amazing.”

Amani has had three litters since Nick, and was recently seen frolicking with members of her third litter. Cubs from the first two litters are now at the San Diego Zoo Safari Park and the Dallas Zoo, and two females from the third litter have been assigned to an exhibit at Walt Disney World.

Crosier watched as the big cat stretched and twisted her body to lick an adoring cub. “Amani has been an excellent mother,” she said.

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