Mixing mala: how genetics informs threatened species management

A recently published population genetic study of mala (rufous hare-wallabies) has provided a way forward for conservation efforts.

One of the smallest members of the kangaroo family, the 1-2 kg mala, also known as the rufous hare-wallaby (Lagorchestes hirsutus), was once widespread and common throughout the deserts of central and western Australia. Due to introduced predators and habitat changes they are now extinct in the wild on mainland Australia, but still survive in captivity and on several islands off the coast of Western Australia.

Ensuring the long-term survival of the remaining populations and increasing their number is vital for mala conservation. Small populations are likely to have low genetic diversity and so be at elevated risk of extinction. In addition, two of the island populations are currently regarded as separate subspecies, which potentially complicates their management, particularly when it comes to planning future reintroductions.

Our study examined the levels of genetic diversity within and genetic differentiation amongst the three surviving populations: the captive mainland population and those found on the adjacent Bernier and Dorre Islands in Shark Bay, WA. Levels of genetic diversity were very low in both island populations but comparatively high in the captive mainland population. While all three populations were found to be genetically differentiated, the two island populations were more similar to each other than either was to the mainland. And there were indications that until a few thousand years ago the two islands populations had been part of a single population.

Although each island population is currently regarded as a separate subspecies, this is not consistent with the pattern of differentiation revealed by our data, and we would recommend that only a single island subspecies be recognised. The low level of genetic diversity detected in each of the island populations is a cause for concern, although a genetically more diverse population could be created by mixing individuals from both islands in future reintroductions.

Dr Mark Eldridge, Principal Research Scientist, Terrestrial Vertebrates, Australian Museum Research Institute

Dr Linda Neaves, Post Doctoral Researcher, Australian Centre for Wildlife Genomics, Australian Museum Research Institute and Royal Botanic Garden Edinburgh

More information:

• Eldridge, M.D.B., Neaves, L.E. and Spencer P.B.S. 2018. Genetic analysis of three remnant rufous hare-wallaby (Lagorchestes hirsutus) populations in arid Australia. Australian Mammalogy on line.