Scientists use DNA from poop to save the world’s rarest marsupial

The Gilbert’s potoroo, a critically endangered species found only in Western Australia, has fewer than 150 animals left in the wild. Scientists from ECU and the Department of Biodiversity, Conservation and Attractions (DBCA) are working together to better understand what the small marsupials eat so conservation teams can identify suitable new habitats and help secure the species’ future.

“We are looking to recover the species through translocations, which is moving organisms from one location to another to create an insurance population in case anything was to happen in their existing populations,” School of Science PhD student Rebecca Quah explains.

“In doing that, one of the challenges was trying to determine what they are eating and where those resources can be found. Mycophagus — or fungi-eating mammal diets are quite hard to study because a lot of fungi remain undescribed.”

Using DNA From Scat To Study Diets

To investigate the potoroo’s diet, researchers used environmental DNA (eDNA) metabarcoding on scat (faeces) samples. The technique is becoming increasingly popular in wildlife research because it allows scientists to study animals without disturbing them.

“Traditionally, researchers would go through undigested material in scats to study animal diets, but trying to identify fungal spores remained a challenge,” Ms. Quah said.

“This research used a molecular technique, known as eDNA metabarcoding to decipher what animals are eating. It’s a non-invasive way of studying diet and all you need are fresh scats from the environment.”

The team also examined whether the diets of more common fungi-eating mammals overlapped with the Gilbert’s potoroo. Researchers focused on species that historically shared the same habitats.

“We examined quokka, quenda and bush rat scats and found that there was some overlap in the diet of the four mammals, and that habitat use between the quokka and potoroo were also really similar,” Ms. Quah said.

“Based on our results, we recommend focusing on areas where all three species persist together as an indicator of suitable food, or habitat, for future potoroo translocation sites.”

Rediscovered After Being Thought Extinct

Gilbert’s potoroo was once believed to have disappeared entirely before being rediscovered in 1994. Since then, conservation teams have tried several approaches to increase the population.

“Soon after their rediscovery, breeding them in captivity was tried, but that didn’t work out, particularly because of how picky they are with their food resources,” she said.

“This is why wild-to-wild translocations are so important. In 2015, a bushfire destroyed 90 per cent of core potoroo habitat in Two Peoples Bay, which is home to the only natural population of Gilbert’s potoroo. Fortunately, insurance populations had been established on Bald Island and in a fenced enclosure at Waychinicup National Park by DBCA.”

DBCA Research Associate Dr. Tony Friend said researchers are now searching for another suitable mainland site to establish an additional population. The species is currently spread across four locations, including two islands off the coast of Western Australia.

“The search for new translocation sites is an important next step in the recovery of Gilbert’s potoroo from near extinction. This publication shows that examining the fungal diet of mammals that occur with the potoroo can help in deciding where to establish new populations,” Dr. Friend said.

Why Fungi-Eating Mammals Matter

Ms. Quah’s broader PhD research focuses on the conservation and relocation of fungi-eating mammals, which play an important role in maintaining healthy ecosystems.

“Fungi-eating mammals are ecosystem engineers — they dig for fungi which helps in soil turnover, and they act as vectors for fungal spore dispersal.

“Fungi have several ecological functions, including having mutually beneficial relationships with plants, so mycophagous mammals are really important in maintaining healthy ecosystems.

“Unfortunately, many of Australia’s mammals are threatened because of predation from introduced cats and foxes. That is why it is vital that we do everything we can to help protect our native wildlife, and translocations are one important way to accomplish that goal.”