Captive Breeding: A Key to Stop Extinction? | Wild Hope Explains

This is the frog ark in Panama. Some species here only exist in captivity. In the wild, they're already extinct. Around the world, labs like this are breeding endangered species that might not survive on their own. For some of our planet's rarest species, captive breeding may be their best shot for survival. Here in the ark, amphibians are being kept safe from a disease called chytrid, which is wiping out wild populations. For these species to survive, they need to rebuild their numbers fast. But that's not always easy in captivity. Many animals rely on external signals, like seasons, temperature, and humidity, to cue their reproductive cycles. These cues trigger the release of hormones, which themselves trigger the production of eggs and sperm. Animals in captivity, like this critically endangered variable harlequin frog, often need help kickstarting the process. For that, scientists turn to assisted reproduction. We're altering their physiology at some point and their hormonal cycles. They don't have the correct cues for their brains to react and say, OK, this is a reproductive cue. Let's go and breathe. Here's where ARTS, or assisted reproductive technology, come in place. The first step is hormonal simulation, using a cocktail of hormones to encourage the production of sex cells. It took years for Della Tonia and her team to perfect the recipe. Once injected and producing sex cells, some species can be left to mate on their own. The second option is artificial fertilization. This approach is a faster way to produce more offspring. And there's another important benefit. The scientists get to decide which female's eggs are fertilized by which male's sperm. That's critical when breeding small populations, because it can help preserve genetic diversity. In the wild, large populations can mix and mingle, leading to lots of healthy genetic variability. In smaller, fragmented, or captive populations, the gene pool may become bottlenecked. That means a higher chance of inbreeding, which results in less genetic diversity over time, and a greater risk of disease or harmful mutations. Captive breeding programs go to great lengths to avoid genetic bottlenecks. Many of them are centered at zoos, which work together to build robust, diverse populations. One shining example is the golden lion tamarin. In the 1970s, while golden lion tamarin numbers in Brazil dropped to only 200 individuals due to poaching and deforestation. The collapse spurred a program across 150 zoos worldwide to breed more tamarins in captivity. At first, breeding tamarins was a challenge, until the Smithsonian National Zoo compiled some basic research on how tamarins feed, socialize, and mate. The techniques allowed all the zoos to keep their tamarins healthy, but in order to prevent populations from inbreeding, they had to strategically pair mates between institutions. For the tamarins, and many other species, zoos use stud books to keep track of every captive animal's genetic lineage. They mix and match between zoos, ensuring that mating pairs pass on as much variation as possible. The golden lion tamarin project was a massive success. By 1984, zoos began releasing healthy, captive-born tamarins back into the forests of Brazil. By 2014, the wild population had grown to almost 4,000, all thanks to the zoo's strategic captive breeding programs. Around the world today, there are hundreds of other endangered plant and animal species being bred in captivity. These populations are often their wild counterparts' greatest protection against disease, habitat loss, and other threats. They also give scientists the chance to study behaviors and genetics in controlled settings, and to prepare for responsible releases into the wild. The next time you visit a zoo or aquarium, ask if they're involved in any captive breeding programs. It's a great way to learn about the important role zoos play in conservation, and the scientific work that makes it all possible. Explore these stories and many more from Wild Hope by visiting wildhope.tv, or watch the full collection now, right here on PBS Nature on YouTube.