Imagine discovering an animal species you thought had gone extinct was still living – without laying eyes on it. Such was the case with the Brazilian frog species Megaelosia bocainensis, whose complete disappearance in 1968 led scientists to believe it had become extinct. But through a novel genetic detection technique, it was rediscovered in 2020.
Such discoveries are now possible thanks to a new approach that recovers and reads the trace amounts of DNA released into the environment by animals. It’s called environmental DNA, or eDNA – and it takes advantage of the fact that every animal sheds DNA into its environment via skin, hair, scales, feces or bodily fluids as it moves through the world.
As wildlife biologists at the University of Florida’s Whitney Laboratory for Marine Bioscience & Sea Turtle Hospital, we use eDNA to track a virus responsible for a sea turtle pandemic called fibropapillomatosis, which causes debilitating tumors. We also use eDNA to detect sea turtles in the wild.
But in 2020, human health researchers began repurposing eDNA techniques to track the COVID-19 pandemic. This is a prime example of how research in one area – wildlife conservation – can be adapted to another area – human disease mitigation. Going forward, we believe eDNA will prove to be an essential tool for monitoring both human and animal health.
From Soil Microbes to Sea Turtles
Scientists in the 1980s began hunting for microbe DNA in soil samples. Over the next 20 years, the technique was adapted for use with air and water samples, and scientists started using eDNA to detect larger animals and plants.
While the science behind eDNA techniques is complex, the actual process of collecting and testing a sample is relatively simple. Samples are filtered through very fine paper, which traps loose cells and strands of DNA. The techniques to read what DNA is present are the same as those used for tissue or blood samples, usually quantitative polymerase chain reaction or whole genome sequencing. Scientists can either read all of the DNA present from every organism – or target just the DNA from species of interest.
Scientists now routinely use eDNA to detect endangered wildlife and invasive species. The ability to tell whether an animal is present without ever needing to lay eyes or a lens on it is an incredible …read more