A new study found a more probable cause for the extinction of Darwin’s Frog. Scientists previously believed that deforestation was the culprit but now an epidemic fungus is to blame.
The Darwin’s frog was first described by Charles Darwin himself in December 1834 when he found it in Chile’s western coast in the Lemuy island. At first scientists thought that there is only one type of Darwin’s frog species but later on, after careful study, realized there were two: the northern Darwin (Rhinoderma rufum) and the southern Darwin (R. darwinii) frogs.
Both species are said to have been endangered for several years. However, the northern Darwin has gone extinct as it was last found in the wilds twenty years ago and the southern Darwin will soon too. Scientists say that their extinction was caused by the fungus disease called chytridiomycosis, which is the culprit for amphibian mortality around the globe.
“Amphibians have inhabited the earth for 365 million years, far longer than mammals. We may have already lost one species, the northern Darwin’s frog, but we cannot risk losing the other one,” said co-author Claudio Soto-Azat of Chile’s Andres Bello University.
Before this discovery, scientists thought that the extinction of the northern Darwin was caused by loss of habitat. But the researchers did not believe this due to the fact that the southern frog species were losing population even in areas where their habitat was not destroyed.
Chytridiomycosis or simply Chytrid disease is developed through the spread of the Batrachochytrium dendrobatidis (Bd) fungus. It is taking its toll on many amphibians around the world for twenty years. This fungal epidemic was first discovered in Queensland Australia in 1993 when frogs were found dying because of the disease. Similar outbreaks were found before in South America, which inspired the researchers to investigate whether Chytridiomycosis is causing the death of Darwin’s frog species.
Their investigations, which involved getting Darwin’s frogs, proved that their speculations were correct. About 12.5 percent of the frogs were found positive with Chytrid. The rate of chytrid were compared with those preverved during the period 1970-1978 and they found that one percent was chytrid-positive. They concluded that this fungus is to blame for the Darwin’s frogs’ population decline.
The study was published in the Nov. 20 issue of PLOS One.
