Newcastle researchers have helped initiate a bid to save the endangered koala species by integrating frozen koala sperm into captive management programs.
The first-of-its-kind model reveals biobanking and assisted reproduction could become a reality for koalas by leveraging the existing technology used to help humans conceive.
Published in the international journal, Animals, the model would significantly help captive breeding programs retain genetic diversity and drastically cut the costs required to deliver management programs.
Co-author and conservation scientist at the University of Newcastle, Dr Ryan Witt, said koala biobanking and assisted breeding conservation programs could future-proof the species.
Koalas face extinction by 2050 without intervention.
“Currently, we have no optimised tools that can store live koala reproductive material, such as sperm,” Dr Witt said.
“So, we have no insurance policy against natural disasters like the 2019-2020 bushfires that threaten to wipe out large numbers of animals at the one time.
“If the koala population dies in these kinds of fire events, there is no way to bring them back or preserve their genetics.”
The latest figures revealed that koala populations across the state have fallen between 33 and 61 per cent since 2001.
At least 6400 koalas were estimated to have been killed in the Black Summer bushfires alone.
“Biobanking, if developed for the koala, would offer a solution to store or “bank” live koala genetics by freezing sex cells such as sperm,” Dr Witt said.
“The frozen sperm can then be used to impregnate female koalas in breed-for-release programs, using assisted reproductive technology.”
A cost-effective option
Dr Witt said their model showed a five to 12 fold reduction in overall program costs of current captive koala breeding programs if biobanking and assisted reproduction were incorporated.
“Captive breeding programs require larger koala colony sizes to prevent inbreeding … but by integrating assisted reproduction, we can reduce the number of koalas needing to be in captivity, lower costs and improve genetic diversity,” Dr Witt said.
“This would free up valuable conservation funding to support a greater number of species, or to support other koala conservation efforts such as habitat restoration.”
Through his PhD research at the University of Newcastle, lead author Dr Lachlan Howell has spent years developing and analysing this robust model for various endangered animals but believes it offers the koala the most promise.
“The beauty of applying assisted reproductive technologies to the koala population is that much of the foundation has already been laid, much of the infrastructure is already in place,” Dr Howell said.
“We’ve identified 16 wildlife hospitals and zoos across Australia that could act as nodes to collect koala sperm and help integrate assisted reproduction.”
He added that recent advances in science showed that artificial insemination using fresh and chilled sperm worked in koala populations.
“The hurdle is trying to freeze sperm and make use of it,” he said.
“All that is needed now is more research and funding to tweak existing assisted reproduction technologies so that we can cryopreserve koala sperm, just like we do for humans.”
The genetic benefit
While captive breeding programs remain a powerful tool to save koalas, they face significant high costs and genetic diversity challenges.
Dr Howell said genetic issues in koalas could lead to reproductive dysfunction and infertility.
“These issues can also compromise survival, disease resistance and the species’ ability to adapt to changing environmental conditions from climate change,” Dr Howell said.
“Our modelling shows that supplementing frozen founder sperm into koala colonies using various assisted reproductive technologies, such as those common in agriculture and human fertility, could significantly reduce inbreeding.
“It would also allow captive programs to hold smaller colonies whilst still meeting optimal genetic diversity targets.”
By using frozen sperm, scientists can reintroduce genetic variation into wild koala populations without having to relocate koalas.
“In NSW, for example, koala populations are declining rapidly in some locations, so they would greatly benefit from the introduction of biobank material from other unique populations to help manage genetic diversity,” Dr Howell said.
If cryopreservation is made possible for koalas, it will provide an opportunity to recover and biobank genetic material from koalas who may have died in bushfires or been hit by cars.
Proven success in a similar program
Dr Howell voiced confidence in the program after an applied research effort to save the black-footed ferret from near-extinction proved successful in North America.
“In 1981, the black-footed ferret population was reduced to just 18 animals, and now through years of research, assisted reproduction has become a reality for the animal,” Dr Howell said.
“Sperm frozen for 20 years was used to artificially inseminate some of the captive-bred ferrets, which were becoming more inbred over time.
“This was crucial to reintroduce genetic variation in the captive population, which over time suffered reproductive complications from inbreeding.”
Dr Howell said thousands of ferrets had since been born and released into the wild.
“In this case, researchers cryopreserved black-footed ferret sperm many years before they figured out how to use the sperm in assisted breeding,” he said.
“This may be the pathway we need to take to ensure the future of Australia’s much-loved koala.”
Maia O’Connor