The isolated Yellow-footed Rock-wallaby populations of today, were once connected
Although populations of the threatened Yellow-footed Rock-wallaby are now patchily distributed across the mountain ranges of the southeastern Australian semi-arid zone, a new genetic study has revealed evidence of historic connectivity.
The Yellow-footed Rock-wallaby, Petrogale xanthopus is the largest and most visually striking of the 17 Rock-wallaby species in Australia, and yet little genetic research has been undertaken on these species (and mammals in arid Australia overall). It is only one of three Petrogale species that inhabit the arid regions of Australia, even though these cover ~70% of the continent. Yellow-footed Rock-wallabies consists of two subspecies, P. xanthopus celeris in southwestern Queensland and P. x. xanthopus in southeastern South Australia and western New South Wales.
An adult Yellow-footed Rock-wallaby, Petrogale xanthopus xanthopus comes to drink at a waterhole in Brachina Gorge, Flinders Ranges, SA.
Image: Craig Smith© Craig Smith
Due to habitat degradation from introduced herbivores, introduced feral predators and changed fire regimes, Yellow-footed Rock-wallabies have declined throughout much of their range. The reduction in habitat and connectivity between populations is likely to have reduced genetic diversity and migration between populations, ultimately impacting their ability to adapt to change.
Although usually associated with steep rocky areas, Yellow-footed Rock-wallabies, Petrogale xanthopus xanthopus will also utilise more flat open areas for foraging.
Image: Craig Smith© Craig Smith
Within P. x. xanthopus, populations are now patchily distributed across the Flinders Ranges, Gawler Ranges and Olary Hills in South Australia and active conservation management has been a priority for decades, with some populations recovering. After significant trapping and sampling efforts from 2005-2012, we evaluated the genetic diversity and connectivity of populations to help understand their history of gene flow and provide a basis for ongoing management. Our data from 2005-2012 indicate a highly fragmented population landscape and associated reduced genetic diversity within populations and evidence of some populations going through bottlenecks. In addition, there is limited evidence of contemporary gene flow among populations, particularly between the mountain range systems. Despite this contemporary pattern, the historical pattern of diversity reveals much greater connectivity, indicating that these populations were previously intermixing.
Given the need to maximise genetic diversity and the ability for species to adapt to changing environments and climates, we recommend mixing of populations across South Australia at a broad scale to reduce the chance of continued diversity loss. This will ultimately increase the potential for populations to adapt and survive into the future.
Dr Sally Potter, Research Associate, Australian Museum Research Institute; Postdoctoral Fellow, Australian National University
Dr Mark Eldridge, Principal Research Scientist, Australian Museum Research Institute
More information:
Potter, S., Neaves, L.E., Lethbridge, M., Eldridge, M.D.B. 2020. Understanding historical demographic processes to inform contemporary conservation of an arid zone specialist: the yellow-footed rock-wallaby. Genes 11: 154. (Special Issue: ‘Marsupial Genetics and Genomics’) https://doi.org/10.3390/genes11020154
