Bulletin

Issue: March 2004

Research in Action

Sorting out the relatives in the Kangaroo family

What is the link between Dr Mike Westerman examining mitochondrial DNA sequences of both extinct and living kangaroos in his La Trobe University genetics laboratory -and the best way to spend scarce conservation funds?

'A very close link', says Dr Westerman, 'because our work with kangaroo DNA is slowly piecing together a detailed picture of relationships between the various parts of the kangaroo family.

'The discovery, or confirmation, that one or more members of the family have no close relatives-and it is therefore imperative to conserve them-has a huge bearing on which species need to be given higher priority for conservation.'

A reader in Marsupial Molecular Evolution in La Trobe's Department of Genetics, Dr Westerman and his colleagues have recently confirmed through mitochondrial DNA sequencing what others had suspected from morphological comparison-that Western Australia's very rare Banded Hare Wallaby has no kangaroo cousins. It has effectively travelled alone down the evolutionary path for about 20 million years.

'It's a loner-having diverged from other kangaroos all those years ago-and for this reason must warrant the greatest attention of conservationists,' Dr Westerman says.

The small, nocturnal Banded Hare Wallaby (Lagostrophus fasciatus), once common in semi-arid regions of southern WA, occurs in the wild now only on Bernier and Shark islands in Shark Bay and is classified as 'vulnerable'.

Fitting the Banded Hare Wallaby into the evolutionary jigsaw puzzle of the larger kangaroo family has been among the principal research interests of Dr Westerman and two other world experts in marsupials, Dr Carey Krajewski of the University of Southern Illinois and Dr Mark Springer of the University of California (Riverside).

All kangaroos evolved from a possum-like tree-dwelling marsupial about 45 million years ago and research since the settlement of Australia has defined three distinct living groups. One group comprises the larger kangaroos, wallabies and pademelons, the second comprises the bettongs and potoroos, and the third is thought to contain the last living representative of another group, the Sthenurines or short-faced kangaroos.

'Our group set out to use DNA sequences, both mitochondrial and nuclear, from both living kangaroos and from museum specimens of extinct species, in order to build up a complete picture of relationships in the kangaroo family. The DNA of representative species of every sub group of the first two groups has been sequenced, giving us sound knowledge of their relationships to each other,' Dr Westerman said.

'However it's not so easy to place the Banded Hare Wallaby which may, or may not, be a member of the Sthenurines sub group otherwise thought to have been totally extinct.

'We have found that the DNA of the Banded Hare Wallaby is, genetically, quite distinct from all other living kangaroos. We are not yet sure whether it belongs to the Sthenurines group since there are no known living species-but we now have a chance to find this out.

Two years ago, sub-fossil remains of a broad range of very well preserved Pleistocene mega fauna species-including Sthenurines kangaroo- were found in a cave on the Nullarbor Plain.

'Much more importantly for us, the remains on the kangaroo fossil were in good enough condition for the Museum of WA to send a sample for analysis to the Ancient DNA Laboratory run by Professor Alan Cooper at Oxford University. If he is able to obtain DNA sequences from this animal, we can then compare them to those of the Banded Hare Wallaby and thus ascertain whether it is of that family.

'We eagerly await Professor Cooper's results.'•

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