Marsupials under the microscope

A conservation genetics project on Kojonup Reserve is guiding the management of one of Bush Heritage’s sweetest marsupial residents – the Red-tailed Phascogale.

University of Western Australia zoology and genetics student Rhiannon de Visser slows down her speech, giving one word, kindly, at a time.

“Single – nucleotide – polymorphisms.” She laughs. “It’s a bit of a mouthful.”

And for most of us, it is indeed. The term, shortened by scientists to ‘snips’, or SNPs, describes variations within an animal’s genetic code.

These variations are distributed throughout an individual’s DNA, and can be used to determine how different animals are related. And for a population of tiny, tree-dwelling marsupials at Bush Heritage’s Kojonup Reserve in south-west Western Australia, information like this could help safeguard their long-term survival.

Rhiannon first laid eyes on a phascogale in 2020, when she assisted on a four-day monitoring trip to assess the health of the Kojonup population. The survey marked a decade since 30 of the gentle-natured creatures, with bushy tufts on the end of their long tails, were released at Kojonup in Bush Heritage’s first-ever species translocation, in collaboration with the WA Department of Biodiversity, Conservation, and Attractions.

In 2021, with the population breeding and even expanding onto neighbouring properties, the translocation is considered a success. And for Red- tailed Phascogales, which now inhabit less than 1% of their former range across Australia, that’s great news.

But with climate change and changed fire regimes listed as key threats for phascogales, adaptability is critical, and that’s where Bush Heritage ecologist Angela Sanders, who was present at the initial translocation, says more might need to be done to secure the Kojonup population’s future.

“We need to know more about the genetic makeup of this population,” says Angela.

The results of Rhiannon’s DNA analysis will tell Angela and her team whether the original 30 animals translocated in 2010-11 provided adequate genetic diversity to sustain a diverse population long-term at Kojonup. They'll also indicate whether other phascogales that may have been living in the surrounding landscape have bred with the Kojonup population.

Rhiannon explains some of the benefits of genetic diversity.

“If there's more genetic diversity then the population will be more resilient in the face of change."

"For example, if a disease was to go through the population, if all of those animals all have the same genetic makeup, then they’ll all be susceptible to the disease.”

“But our hope is that if you have more genetic diversity then some of those animals would be less susceptible or even resistant. In that case, the population wouldn't be wiped out. And those animals that were resistant would be able to contribute that resistance to further generations.”

While Rhiannon’s previous volunteering contributions have provided crucial information to Bush Heritage’s conservation management plans, this is the first time she'll be contributing her genetics credentials by putting phascogale DNA under her microscope.

“You basically strip away the tissue using a kit and break open the cells to get the DNA,” says Rhiannon.

The lab that Rhiannon will carry out her work in is a far cry from the She-oak and Wandoo woodlands in which she helped to collect the first of the samples. In November 2020, Rhiannon watched seven tiny Red-tailed Phascogale babies wriggling and writhing in a nesting box, lined with alpaca wool, witnessing more evidence of the growing population. (Samples from the babies were not taken, as per ethics guidelines.)

The precariousness of small, isolated populations like this one are exactly what drove Rhiannon to study zoology.

“I want to be part of this effort to conserve our beautiful environment and the animals around us. I want to be a part of the fight to save these phascogales,” she says.

Angela, who has been monitoring the phascogales at Kojonup ever since their initial release, considers them one of two animals she most likes to work with (alongside Malleefowl). “I’m thrilled that the phascogales are doing so well,” she says. “I’ve developed quite a soft spot for them.”

Angela is pleased that the genetic study of the population, which has been proposed for some time, has been given the go-ahead this year thanks to the generous support of Peter and Maxine Wilshaw. The results will help to forge the next steps in securing the future of the population.

In May this year, Rhiannon and Angela will return to Kojonup to collect more DNA samples before the study begins in earnest.

“If we find that the genetics are too similar,” says Angela, “we'll consider bringing in new animals to diversify the genetic pool.”