Conservation dynamics: Should we change species to save them?

For tens of millions of years, Australia has been a playground for evolution, and the land Down Under lays claim to some of the most remarkable creatures on Earth. It is the birthplace of songbirds, the land of egg-laying mammals and the world capital of pouch-bearing marsupials, a group that encompasses far more than just koalas and kangaroos. (Behold the bilby and the bettong!) Nearly half of the continent’s birds and roughly 90 percent of its mammals, reptiles and frogs are found nowhere else on the planet.

Australia has also become a case study in what happens when people push biodiversity to the brink. Habitat degradation, invasive species, infectious diseases and climate change have put many native animals in jeopardy and given Australia one of the worst rates of species loss in the world.

In some cases, scientists say, the threats are so intractable that the only way to protect Australia’s unique animals is to change them. Using a variety of techniques, including crossbreeding and gene editing, scientists are altering the genomes of vulnerable animals, hoping to arm them with the traits they need to survive.

“We’re looking at how we can assist evolution,” said Anthony Waddle, a conservation biologist at Macquarie University in Sydney. It is an audacious concept, one that challenges a fundamental conservation impulse to preserve wild creatures as they are. But in this human-dominated age — in which Australia is simply at the leading edge of a global biodiversity crisis — the traditional conservation playbook may no longer be enough, some scientists said. “We’re searching for solutions in an altered world,” said Dan Harley, a senior ecologist at Zoos Victoria. “We need to take risks. We need to be bolder.”

The helmeted honeyeater is a bird that demands to be noticed, with a patch of electric-yellow feathers on its forehead and a habit of squawking loudly as it zips through the dense swamp forests of the state of Victoria. But over the last few centuries, humans and wildfires damaged or destroyed these forests, and by 1989, just 50 helmeted honeyeaters remained, clinging to a tiny sliver of swamp at the Yellingbo Nature Conservation Reserve.

Intensive local conservation efforts, including a captive breeding program at Healesville Sanctuary, a Zoos Victoria park, helped the birds hang on. But there was very little genetic diversity among the remaining birds — a problem common in endangered animal populations — and breeding inevitably meant inbreeding. “They have very few options for making good mating decisions,” said Paul Sunnucks, a wildlife geneticist at Monash University in Melbourne.

In any small, closed breeding pool, harmful genetic mutations can build up over time, damaging animals’ health and reproductive success, and inbreeding exacerbates the problem. The helmeted honeyeater was an especially extreme case. The most inbred birds left one-tenth as many offspring as the least inbred ones, and the females had life spans that were half as long, Dr. Sunnucks and his colleagues found.

Without some kind of intervention, the helmeted honeyeater could be pulled into an “extinction vortex,” said Alexandra Pavlova, an evolutionary ecologist at Monash.