Sourthern Corroboree Frog. Image © Corey Doughty

The Southern Corroboree Frog

Genetic engineering of the Southern Corroboree Frog remains speculative, and faces many challenges. Australia’s regulatory system appears ill-equipped to assess irreversible genetic modifications in endangered species within protected areas. Meanwhile, captive selective breeding is advancing, and natural recovery in related species shows that, given time and habitat protection, evolutionary adaptation is possible.

A species on the brink

The Southern Corroboree Frog (Pseudophryne corroboree) is found in the Snowy Mountains of Kosciuszko National Park in New South Wales, Australia. In decline since the mid-1980s, it is now functionally extinct – unable to survive in the wild without human support.1

Why is the Southern Corroboree Frog critically endangered?

The primary cause of decline is chytridiomycosis – a disease caused by the amphibian chytrid fungus (Batrachochytrium dendrobatidis) – which has spread globally, causing mass amphibian declines and extinctions. Additional pressures include habitat loss and degradation, driven by climate change, invasive weeds, and other disturbances.2

Can genetic engineering help save the species?

Scientists are now exploring genetic engineering to create amphibians immune to chytrid infection. In December 2024, the Colossal Foundation announced $3 million over three years in funding for this technology, starting with the cane toad (Rhinella marina) as a model before targeting critically endangered species like the Southern Corroboree Frog.34

Engineering resistance to chytrid fungus faces fundamental challenges

Genetic engineering in frogs: Scientific hurdles and unknowns

A captive-bred Southern Corroboree Frog © Corey Doughty

Scientists at the University of Melbourne plan to engineer a transgene containing a single-chain antibody gene from the alpaca (Vicugna pacos)3 and insert it into the frog’s genome. The goal is to enable the frog – and potentially many other amphibian species – to produce antibodies against the chytrid fungus.5

Fundamental challenges include:

  • Pathogen complexity: The Batrachochytrium dendrobatidis fungus comprises many continually evolving strains with varying virulence.6
  • Technical limitations: Amphibian genetic engineering lags far behind mammalian techniques. The size of the Corboree Frog genome, first sequenced in 2025, is three times larger than the human genome.1 In addition, the frogs take 4-5 years to reach sexual maturity. Developing and validating a genetic modification protocol for the frog could take many years.
  • Transgene insertion: Scientists must ensure that inserting the transgene does not cause unintended side effects, and that in the absence of the pathogen, the transgene is not so rapidly removed by natural selection that ongoing, large-scale releases become permanently necessary.7
  • Long timelines: At least 10 to 20 years, as well as long-term funding, are needed for this effort to — potentially — succeed. 

What happens if we release genetically modified frogs into the wild?

The Colossal Foundation says engineered amphibians will be “reintroduced into the wild, where their immunity can spread through natural selection.”3 This would make the intervention irreversible – once released, the modified genes would permanently alter the species’ genome.

While this approach targets chytrid infection in one species, it does not address the fungus’ continued spread via global amphibian trade or contaminated water.8 Nor does it tackle other major threats like habitat degradation, which weaken frog populations and increase vulnerability to disease.2

Geographic range of the Southern Corroboree Frog. Red area: extinct. Yellow area: extant. Image © IUCN

Who decides? Gaps in regulation and oversight

Under Australia’s Gene Technology Act 2000, the environmental release of genetically modified (GM) frogs would require a Dealings Involving Intentional Release (DIR) licence from the Office of the Gene Technology Regulator (OGTR).9 To date, no such licence has been granted for any GM animal under Australian law10 – although an application has been submitted for the commercial release of a GM Aedes aegypti mosquito strain in Queensland.11

In addition, because the intervention involves a listed threatened species and release into Kosciuszko National Park, it would also require assessment under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) – again without precedent.

Related species show signs of natural recovery

What is working now: Breeding, habitat restoration and natural resistance

While genetic engineering remains speculative, proven conservation strategies are already achieving results. Captive breeding has been underway for nearly 30 years, with over 2,000 Southern Corroboree Frog eggs released to Kosciuszko National Park.12

Encouragingly, related species show signs of natural recovery without genetic modification. Endangered Alpine Tree Frogs (Litoria verreauxii alpina) have stabilised despite chytrid, developing strategies such as increasing reproductive output when infected.13 Similarly, endangered Fleay’s Barred Frogs (Mixophyes fleayi) are evolving resistance14 – alongside habitat restoration initiatives15 – showing that natural adaptation is possible with time and suitable environments.

New research shows that basking sites and altered pond temperatures can help clear chytrid infections in endangered frogs.16 With around 20% heritability of chytrid resistance already documented in Southern Corroboree Frogs,17 selective breeding could strengthen natural defences without the risks of genetic engineering. Such breeding, supported by genome information, is already underway.1 

Snowy Mountains as seen from Kosciuszko Lookout. Image © Cimexus

Sources

  1. Kosch T (2025). By sequencing the genome of the endangered Southern Corroboree Frog, we could save it. University of Melbourne website. https://pursuit.unimelb.edu.au/articles/by-sequencing-the-genome-of-the-endangered-southern-corroboree-frog,-we-could-save-it [↩] [↩] [↩]
  2. Office of Environmental Heritage (NSW) (2012). Southern Corroboree frog (Pseudophryne corroboree) and Northern Corroboree frog (Pseudophryne pengilleyi) national recovery plan. https://www.dcceew.gov.au/environment/biodiversity/threatened/recovery-plans/southern-corroboree-frog-and-northern-corroboree-frog [↩] [↩]
  3. Colossal Foundation website. https://colossalfoundation.org/project/saving-amphibians-from-chytrid-fungus [↩] [↩] [↩]
  4. Colossal Foundation press release (2024). https://www.businesswire.com/news/home/20241216229333/en/The-Colossal-Foundation-Makes-First-Donation-of-US-%241M-as-Part-of-%243M-Commitment-to-Combat-Chytrid-Fungus-Save-Amphibians-from-Mass-Extinction-and-Protect-Endangered-Ecosystems [↩]
  5. University of Melbourne, Frankenberg Lab website. https://frankenberg.science.unimelb.edu.au/chytrid-resistance [↩]
  6. Davidson MJ et al (2025). Influence of Batrachochytrium dendrobatidis isolate and dose on infection outcomes in a critically endangered Australian amphibian. Fungal Ecology. https://www.sciencedirect.com/science/article/pii/S1754504824000680 [↩]
  7. Mathis E (2025). It’s not easy being green. Australian Geographic. https://www.australiangeographic.com.au/nature-wildlife/2025/05/its-not-easy-being-green [↩]
  8. Fisher M and Garner TWJ (2007). The relationship between the emergence of Batrachochytrium dendrobatidis, the international trade in amphibians and introduced amphibian species. [↩]
  9. Australian Government, Office of the Gene Technology Regulator. https://www.ogtr.gov.au/apply-gmo-approval/apply-dir-licence [↩]
  10. Australian Government, National Gene Technology Scheme (2025). https://www.genetechnology.gov.au/using-gene-technology/agriculture [↩]
  11. Australian Government (2024). Commercial release of a genetically modified (GM) mosquito strain to help prevent dengue outbreaks. https://www.ogtr.gov.au/gmo-dealings/dealings-involving-intentional-release/dir-207 [↩]
  12. Corroboree Frog website. Captive Breeding. https://www.corroboreefrog.org.au/conservation/captive-breeding [↩]
  13. Brannelly LA et al (2025). Devastating disease can cause increased breeding effort and success that improves population resilience. Open Biology. https://royalsocietypublishing.org/doi/10.1098/rsob.240385 [↩]
  14. Hollanders M et al (2022). Recovered frog populations coexist with endemic Batrachochytrium dendrobatidis despite load-dependent mortality. Ecological Applications. https://esajournals.onlinelibrary.wiley.com/doi/10.1002/eap.2724 [↩]
  15. Big Scrub Rainforest Conservancy website (2017). Species in profile – Fleay’s Barred frog. https://bigscrubrainforest.org/learn-more/species-in-profile-fleays-barred-frog [↩]
  16. Waddle A et al (2024). Hotspot shelters stimulate frog resistance to chytridiomycosis. Nature. https://www.nature.com/articles/s41586-024-07582-y [↩]
  17. Roberts R (2025). Scientists Leverage Genomics to Save Endangered Frogs from a Deadly Fungus. The Scientist. https://www.the-scientist.com/scientists-leverage-genomics-to-save-endangered-frogs-from-a-deadly-fungus-73166 [↩]