From matchmaking to setting the right mood, it takes a lot of effort to get endangered species in captivity to breed. Sometimes animals can’t be left to let nature take its course, so people intervene.
Artificial insemination—taking sperm from a male and placing it into the reproductive system of a female—is one such tool in a scientist’s toolkit. But what’s commonplace for people and livestock like cows and sheep is incredibly difficult in wild animals. (See “Infertility in Spanish Pigs Has Been Traced to Plastics. A Warning for Humans?”)
Researchers keep trying, though, because success means more genetically diverse captive populations of animals, which can better weather diseases and environmental changes. Artificial insemination could also help nurse endangered species back from the brink of extinction.
Hope for such efforts made a large leap forward recently with the announcement that researchers had been able to produce Magellanic penguin chicks using artificial insemination—a first for any penguin species.
Black-footed ferrets and giant pandas are the only endangered species routinely produced through a combination of breeding the old-fashioned way and artificial insemination, says Pierre Comizzoli, a research biologist and project leader of the Pan-Smithsonian Cryo-Initiative in Washington, D.C. (See “Is Breeding Pandas in Captivity Worth It?”)
But there have been some successful artificial insemination attempts for other animals, including the white-naped crane and the Przewalski’s horse, he says. (See “First Przewalski’s Horse Born Via Artificial Insemination.”)
Researchers have also had some success with elephants, says Bill Holt, a reproductive biologist with the University of Sheffield in the U.K. and the National Zoo in Washington, D.C.
Indeed, even as the technique faces some obstacles, scientists are working to extend the use of artificial insemination to more and more species. “Research efforts by fairly small numbers of people are beginning to crack [the] problems,” says Holt.
Adrienne Crosier, a reproductive biologist at the Smithsonian’s Conservation Biology Institute (SCBI) in Front Royal, Virginia, who has been trying unsuccessfully to use artificial insemination on vulnerable cheetahs for years, goes further, calling the technique an “amazing tool.”
“And it’s going to be more and more important,” she says. “We’re going to have some milestones with cheetahs in the next decade or so.”
A Wild Challenge
Aside from the challenges of handling wild animals, the lack of knowledge regarding the reproductive biology of many wild species—like koalas or cranes—is perhaps the biggest hurdle, experts say.
Depending on the species, males and females can’t breed or produce sperm or eggs year-round, says the Smithsonian’s Comizzoli. So researchers need to nail down an animal’s reproductive cycle before they can begin to contemplate how to collect semen from a male or when to try to impregnate a female.
Once they have that figured out, scientists need to find the right mix of hormones to give to the females so that they’re receptive to the sperm. Then researchers must determine where in the female’s reproductive system to place the semen so that there is a good chance she’ll become pregnant.
Researchers at the SCBI have been trying unsuccessfully to use artificial insemination on their captive cheetah population since 2003. Wild cheetahs have disappeared from over 76 percent of their range and suffer from shrinking gene pools. Keeping their genetic diversity alive in captivity could one day help revive wild populations.
One of the stumbling blocks is that the female cheetahs don’t react consistently to the hormone therapies researchers give them during attempts at artificial insemination, says Crosier.
Added to those challenges is the fact that some species are simply easier to work with than others. “When you put your hands on [an] animal, especially wild species, because they are stressed and they can be really aggressive,” says Comizzoli, “it can be dangerous.”
That explains why researchers at SeaWorld’s reproductive research organization started their artificial insemination work in penguins with the Magellanics. They’re one of the more easygoing penguin species, says Justine O’Brien, scientific director of reproductive programs at SeaWorld and Busch Gardens in San Diego, California. “They’re very friendly little fellows.”
Plus, “[Magellanic penguins] reproduce quite easily in zoos,” says O’Brien, one of the researchers involved in the penguin efforts.
Although the species isn’t endangered, the penguins do face increasing threats in the wild, she says. “Their breeding grounds in the wild are where climate models have predicted increases in [the number] and intensity of storms,” O’Brien explains.
Magellanic penguins are closely related to endangered species like jackass penguins and Galapagos penguins, says O’Brien. The hope is that once scientists get better at using artificial insemination on the Magellanics, that will pave the way for work on the more difficult penguin species.
It’s already become an important tool for managing captive populations of wild animals.
“Artificial insemination is great for moving genes among facilities, among countries, without moving the animal,” says the SCBI’s Crosier.
It’s also a way to bank semen for the future, says the University of Sheffield’s Holt, since sperm from many species can be frozen and used years later. Semen collected from black-footed ferrets in the 1980s is still being used today.
The ferrets are the first endangered species to be reintroduced to habitats from which they’d disappeared with the help of artificial insemination. It may take years, but scientists are confident that other types of animals will eventually follow suit.
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