For tens of millions of years, Australia It has been a playground for evolution, having some of the most notable creatures on Earth.
It is the cradle of songbirds, the land of egg-laying mammals and the pouched marsupial capital of the world, a group that encompasses much more than koalas and kangaroos. (There's the bilby and the bettong!)
Almost half of Australia's birds and about 90 percent of its mammals, reptiles and frogs are found nowhere else on the planet.
Australia has also become a case study of what happens when people push biodiversity to the limits. Habitat degradation, invasive species, diseases and climate change They have put many animals at risk 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 change them. Using a variety of techniques, including breeding and gene editing, scientists are altering the genomes of vulnerable animalsin the hopes of equipping them with the traits they need to survive.
It's a bold concept, one that challenges a fundamental conservationist impulse to preserve wild creatures as they are. But today, the traditional conservation manual may no longer be enough, some scientists said.
“We are looking for solutions in an altered world,” said Dan Harley, an ecologist at Zoos Victoria. ““We need to take risks and be bolder.”
The helmeted honeycreeper is a bird with a patch of electric yellow feathers on its forehead and a habit of squawking loudly in the dense swampy forests of the State of Victoria. But over the centuries, humans and forest fires have damaged or destroyed these forests and, in 1989, only 50 helmeted honeycreepers remained in the Yellingbo Nature Conservation Reserve. Conservation efforts helped the birds survive, but with very little genetic diversity.
In any small, closed breeding group, genetic mutations can accumulate, damaging the health and reproductive success of animals, and inbreeding makes the problem worse. Without intervention, the helmeted honeycreeper could be drawn into an “extinction vortex,” said Alexandra Pavlova, an evolutionary ecologist at Monash University in Melbourne.
10 years ago, Pavlova and others proposed adding the Gippsland yellow-throated honeycreepers, which live in drier forests, to the breeding group. The two are members of the same species, but are genetically different. Crossing them risked muddying what made each unique and creating hybrids that didn't fit well into either niche. The movement of animals between populations can spread diseases, create invasive populations, or destabilize ecosystems in unpredictable ways.
“It was really just the idea that the population was on the verge of becoming extinct that gave government agencies a push,” said Andrew Weeks, an ecological geneticist at the University of Melbourne who initiated the genetic rescue of the pygmy possum. in danger of extinction in 2010.
Thus, Gippsland birds have been part of the helmeted honeycreeper breeding program at Healesville Sanctuary since 2017. There have been real benefits in captivity, with many mixed pairs producing more independent chicks per nest than pairs consisting of two honeyeaters of helmet. Dozens of hybrid honeycreepers have been released into the wild.
Experts are also working on the genetic rescue of other species, including Leadbeater's possum, a small, critically endangered tree-dwelling marsupial. By 2023, only 34 lowland possums remained. The first genetically rescued calf was born last month.
Scientists hope that the increase in genetic diversity will make animals more resilient. Still, organisms and ecosystems are complex. Genetic interventions “are likely to have some unintended impacts,” said Tiffany Kosch, a conservation geneticist at the University of Melbourne.
In Harley's view, preventing further extinctions will require human intervention. “I think 50 years from now, wildlife biologists and managers will look at us and say, 'Why didn't they take action and opportunities when they had the chance?'” he said.
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