OUR WORK
Australia is a world leader in species extinction and declines, largely due to invasive species.
Our Work | Ending extinction | Photo by Lindy Lumsden
Extinct: Southern gastric brooding frog
- Common name: Southern gastric brooding frog
- Scientific name: Rheobatrachus silus
- Formal national status: Extinct
- Decade of extinction: 1980s
- Expert assessment of extinction causes: Invasive species (Chytrid fungus 98%)
In the mountains of southern Queensland in 1971, biologist David Liem discovered a frog like none ever seen before. It didn’t merely live near water, but was truly aquatic, staying below for hours on end. It reared EXTINCT Primary Cause its young in an amazing way: the mother swallowed her 1980s INVASIVE SPECIES fertilised eggs, and the tadpoles lived in her stomach, to emerge as tiny frogs from her mouth.
The southern gastric brooding frog became world famous and was subject to detailed research, but that had to end when the frog disappeared from streams in the Blackall and Conondale Ranges in the 1970s. Before its disappearance, biologist Glen Ingram studied a wild population at his field site. In 1976 he recorded 59 frogs, 35 the next year, 24 the next, then 2, then zero in 1980. A gastric brooding frog seen by someone else in 1981 became the last one ever seen in the wild.
The extinction is blamed on chytrid fungus (Batrachochytrium dendrobatidis), a pathogen that somehow reached Australia from Asia and caused multiple frog extinctions.
In a submission to the recent senate inquiry into Australia’s extinction crisis, Doctors for the Environment highlighted the loss of this species as a missed opportunity to understand its potential medical benefits. The frogs transformed stomach muscle into a version of uterine muscle, using mediators that might have cured muscle diseases in humans, had they been identified.
The southern gastric brooding frog is the world’s prime example of extinction depriving humanity of a medical resource, although it was far more than that. Inset: Michelle McFarlane (© Museums Victoria)
The book Sustaining Life: How Human Health Depends upon Biodiversity (2010), which was sponsored by the United Nations and IUCN, also highlighted the loss of this frog and the foregone medical insights.
In 2005, an ambitious team of scientists attempted to undo extinction and revive this species. Project Lazarus entailed taking cell nuclei from a dead gastric-brooding frog stored in a freezer by a biologist in the 1970s. These were inserted into the de-nucleated eggs of a related frog. After hundreds of trials the first signs of progress came in 2013 – a donor cell divided into a ball of cells. But although DNA from the extinct frog would build and replicate cells, it would not keep this going in any of the native frogs tested. DNA from the donor frog was interfering. Even so, the world was impressed, and the team won an award from Time magazine. Project Lazarus is on ice for now. Had it succeeded, the thylacine would have been up next.
Extinct
Australia has lost about 100 native plants and animals to extinction since colonisation, most of which were mainly due to invasive species. An estimated 27 of those extinctions occurred since the 1960s.
Learn more about some of Australia’s lost animals: