In this blog post, Nicola Jackson shares the findings from their latest study looking at how sampling air particles to detect DNA can be useful in monitoring and conserving koalas.
Perched high up in a Eucalyptus tree, swaying from side to side, lies a sleepy koala unaware of the means spent each year trying to obtain accurate baseline information about its presence. We have thrown all we could at it, from human led surveys to night spotting, bioacoustics, detection dogs, and drones equipped with thermal cameras. Yet, whilst critical to its conservation and management efforts, finding a koala remains an ambitious, time-consuming, and costly endeavour often producing insufficient results. Little did we know that traces of koalas’ presence and that of its predators along with other native, domesticated, and invasive species, float in the air and can be detected through traces of DNA.
Here, we introduce a promising new tool for detecting threatened species: airborne environmental DNA (air eDNA). This innovative and promising approach affords a potentially scalable, affordable, and easy to use solution for species management and conservation. Airborne eDNA involves the collection of airborne particles, such as pollen, skin cells, or hair, that are shed into the environment by plants and animals. By gathering these particles, we can extract environmental DNA (eDNA) to discover information about the species present in a given area. eDNA has been collected from a range of substrates including water, soil, honey and even spider webs.
To test this technology in detecting a threatened species, the koala, our team at the University of Queensland deployed cloth filters to collect particles that may be floating in the air. These were deployed across four locations in Redland Bay, South-East Queensland. By sequencing eDNA collected from these filters, we were able to detect the presence of a range of different species across the landscape. These included native Australian species, the yellow-footed antechinus, ringtail and brushtail possums, and of course our main objective, the koala. We also detected some common domesticated species, like horse, cow, dog, and pig, as well as threatening invasives like the red fox, European hare, and cane toad.
Whilst our resulting detections are promising, we also acknowledge that as an idea still in its infancy, airborne eDNA may be prone to some teething problems. For example, as with other types of eDNA, such as aquatic eDNA, a large portion of the sequences produced were attributed to humans and other highly abundant species that humans rely on for food and agriculture. These detections soak up precious sequencing reads potentially masking the detection of those that may be lowly abundant, like for instance, threatened species. We also saw that our greatest limitation to detecting species from the air was the lack of genetic reference material to help us identify species.
Despite these incipient difficulties, we demonstrate airborne eDNA presents a promising method for the detection and monitoring of threatened species and their ecological communities. We discuss these results, some of the difficulties airborne eDNA faces and how we may begin to use this technology to monitor our threatened species in our research paper in Journal of Applied Ecology.
Read the full article: “Koalas, friends, and foes – the application of airborne eDNA for the biomonitoring of threatened species” in Journal of Applied Ecology.
