All Creatures Great and Small


As pollution, habitat loss, global warming, and disease increase the number of threatened and endangered species, attempts to protect them are more crucial than ever. That’s where the Frozen Zoo comes in.


By Alisa Opar


Although the cells can be used for cloning, the zoo’s purpose isn’t to create carbon copies of endangered or extinct animals. In fact, it’s quite the opposite. “What we’re trying to conserve is the genetic diversity of species,” says Ryder, which gives animals the best chance of survival in the wild.

As he walks through the labs adjacent to the Frozen Zoo, Ryder explains how samples from, say, a bush buck on the African savannah come to “live” in this frigid repository. Scientists collect samples from animals in zoos and in the wild (often the tab of skin that’s removed when an animal is tagged), and send them to the Frozen Zoo to be deposited. The cells are divided, processed, placed in vials, and then frozen in liquid nitrogen, which preserves them for an estimated 10,000 years. When researchers need a sample, they remove it from the freezer and thaw out the cells.

The zoo’s workings are comparable to a bank—researchers deposit and withdraw samples as needed. “It’s not a mausoleum,” Ryder says, lifting a rack from one of the freezers with gloved hands and getting enveloped in the mist formed from the nitrogen vapor condensing water in the air. “This isn’t supposed to be just a place for the DNA of disappearing species. It’s a tool to prevent extinctions.”

One of the most successful conservation efforts aided by the Frozen Zoo is the California condor recovery project. The program is headed by Mike Wallace, a lanky, tanned wildlife biologist whose office is one floor above and around the corner from the Frozen Zoo. Today he is willing to chat, but only for a few minutes. He’s itching to drive south to Baja, Mexico, to scour a canyon where he’s pretty sure a pair of the endangered birds of prey is tending to an egg. His hunch proves right; the egg was the first to be laid by a California condor living in the wild in more than 60 years. And earlier this year, for the first time in nearly a century, a condor was spotted flying over San Diego.

When the condor preservation program launched in 1980, only 19 of the birds remained in the wild. Today, the condor population has swelled to nearly 300 birds, 135 of which live in the wild. “Condors are as rare and endangered as a species gets, and we came very close to losing them,” says Wallace. “With the Frozen Zoo, we basically have a duplicate population of condors. It’s a hedge for the future.”

The project began by bringing the 19 wild birds into captivity at the San Diego Zoo, where they joined eight others already there. Then scientists banked DNA samples from these 27 birds in the Frozen Zoo. Those samples have since been used countless times. One of the first steps to rebuilding the population required figuring out which birds should breed. By studying tissue samples, researchers discovered that the remnant population consisted of birds from three different clans, or families. So they devised a system to breed condors that were least genetically similar, which increases the chance that they’ll survive environmental changes and disease. “That way, each population we have is genetically whole,” says Wallace, so nearby birds can mate without the danger of inbreeding.

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