Animal family tree research the key to survival of endangered species

Detailed genetic history being built up around the world plays an integral part in planning for long-term future of many endangered species

PUBLISHED : Sunday, 03 August, 2014, 4:22am
UPDATED : Sunday, 03 August, 2014, 4:22am

She is not just another girl with a pretty face living in Washington's outermost urban sprawl.

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, Virginia.

Unlike people who pay up to US$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 1,300-hectare institute is at the forefront of an ambitious attempt by United States zoos to save animals threatened with extinction by studying them relentlessly.

Like 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 is being managed," said Sarah Long, director of the population management centre at the Association of Zoos and Aquariums, which guides animal management at 220 accredited zoos.

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

More than 400 biologists and researchers volunteer for stud-book duty, laboriously adding data to a computerised 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 analyse the … birth rate and death rate to predict how many offspring they will 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."

It is actually much deeper than that. Zookeepers not only encourage every animal from ferrets to rhinoceroses to breed naturally, but they are 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 have died, so that it can be resurrected in a way with the birth of offspring through insemination as much as 10 years later.

That happened just last month, when the frozen semen of Jimmy, an Asian rhinoceros, was rushed from the Cincinnati Zoo to the Buffalo Zoo 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 do not die at the instant they do, freezing semen and preserving living cells is a tricky business that has resulted in many failures.

One remarkable success is pandas. A study released last week 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 says. The zoo is expected to celebrate her birth on August 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 an eerie 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 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.

The issue of not allowing unrelated animals to breed exploded into the public realm in February when the Copenhagen Zoo slaughtered a healthy 18-month-old giraffe, Marius, because he could not be used in the zoo's breeding programme.

Marius's genes were already well represented in that zoo's population. So the managers fed Marius a last meal of rye bread, his favourite, and killed him with a shot from a bolt gun. In a step that drew worldwide condemnation, they butchered his corpse in front of zoo visitors, many of them children, and fed it to lions.

Some critics accused zoos of trying to play God in the animal kingdom, but American scientists have heard enough of that.

"Certainly I don't think we're playing God," said Barbara Durrant, the reproductive physiologist who oversees the research arm that houses the "frozen zoo" of semen and biological material of 9,000 birds, reptiles, mammals and other animals.

What happened in Copenhagen is extremely rare, where an animal was put down even as other zoos in Europe wanted to take it. That death is nothing compared with the countless animals that have disappeared because of habitat loss caused by humans, biologists said.

A special issue of Science, published online last week, is devoted to what it calls the startling rates of animal declines and extinctions "through the destruction of wild lands, consumption of animals as a resource or a luxury, and persecution of species we see as threats or competitors".

"Current research … suggests that if we are unable to end or reverse the rate of their loss, it will mean more for our own future than a broken heart or an empty forest," Sacha Vignieri wrote in the introduction.

Zoos aim to be part of the solution. "We're correcting what human interference has caused," Durrant said firmly.