Discovered by Charles Darwin in 1834, Rhinoderma darwinii (better known as Darwin’s frogs) have been declared extinct after a killer disease is thought to have wiped out entire populations across Argentina.
Although habitat disturbance is recognized as the main threat to the two existing species of Darwin’s frogs (the northern Rhinoderma rufum endemic to Chile, and the southern Rhinoderma darwinii from Chile and Argentina), researchers believe this cannot account for the plummeting population and disappearance of the population.
Conservation scientists found evidence of amphibian chytridiomycosis causing mortality in wild Darwin’s frogs and linked this with both the population decline of the southern Darwin’s frog, including from undisturbed ecosystems and the presumable extinction of the Northern Darwin’s frog.
Chytridiomycosis causes morphological changes in amphibians including reddening of ventral skin and convulsions with extension of hind limbs. The disease can also cause lethargy and failure to seek shelter.
Hundreds of specimens of Darwin’s frogs and other amphibians from similar habitats collected between 1835 and 1989 were tested in order to find DNA pieces of Batrachochytrium dendrobatidis (Bd), a fungus that causes the disease chytridiomycosis. In addition, 26 populations of Darwin’s frogs were surveyed in Chile and Argentina between 2008 and 2012 for the presence of Bd.
Amphibians provide an important ecosystem service by maintaining balance in the environment. Without them insect plagues and their subsequent effect on agriculture and public health would be more frequent. ZSL scientists are working to further understand the reasons behind the extinction of Darwin’s frogs, and ensure the long-term survival of the species.
Source: Allison Winter | ENN