Media reported that it is difficult to determine whether an animal is extinct or extremely good at hiding, especially for animals such as frogs, which are already elusive. But now researchers have shown a new way to track lost species by looking for their loose DNA in the environment. In this way, the team rediscoded several missing frogs in Brazil, one of which has been seen for more than 50 years.
No matter how cunning a creature is, it cannot prevent DNA from being released into the environment through skin, fur, hair, scales, feathers, urine, feces and other waste. This environmental DNA (eDNA) can be tracked and analyzed to let people know which organisms live in an area — even without having to see or capture them directly.
In recent years, eDNA has been used to track fish migration, monitor great white sharks, invading clams and starfish, study ancient human species living in some caves, and even discover scenarios such as the Loch Ness monster as just a giant eel.
Now, researchers at Cornell University are using the technology to track frog species that have been scientifically forgotten for decades. The team began looking for 30 amphibian species in six areas of the Atlantic coast forest and Brazil’s Serrado Prairie, where they were previously known to live.
First, the researchers went into the Brazilian jungle, took samples from streams and ponds, pumped them into filters to capture DNA, and then sealed it for research. When they returned to the lab, the team extracted the DNA and sequenced it genetically, then filtered the DNA of other animals until only frogs were left.
Eventually, the team found eDNA evidence for seven particularly interesting frog species. The headliner is Megaelosia bocainensis, a species that has so far been found only in a single specimen collected in 1968.
The team also found evidence of four species of frogs that were once common in the region but are now rare, as well as two species of frogs found elsewhere — they are thought to have disappeared completely from these areas.
“A small fraction of the DNA in the environment doesn’t tell us how many individuals there are or whether they’re healthy, but it does tell us that the species still exists,” said Kelly Zamudio, lead author of the study. “
The team hopes to collect more eDNA samples from other regions to try to find more signs of these elusive frogs.
The study was published in The Molecular Biology.