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Australia's marvellous marsupials.

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Tuesday 5 February 2008

Chris Dickman, professor, School of Biological Sciences, University of Sydney


Australia's marvellous marsupials

Marsupials are the archetypal Australians.

They feature prominently in Aboriginal art and culture, and they serve as powerful symbols in the affairs of new Australians too. Marsupials appear in enchanting stories for children such as The magic pudding by Norman Lindsay and Possum magic by Mem Fox, and in poems such as Antechinus by AD Hope and Kangaroo by DH Lawrence. They serve as faunal emblems for most Australian states and territories, and as logos for high profile companies such as Qantas and Tasmania's Cascade Brewery. If you wish to establish your Australian credentials, what more recognizable symbol could you choose than a marsupial?

But marsupials are much more than just symbols. They are integral parts of the Australian environment, and their presence is critical for its continued wellbeing. Marsupials toil unseen, performing a remarkably broad and important range of 'ecosystem services' such as dispersing seeds and maintaining soil quality. If they are taken out of the system, we risk not just the loss of productivity and landscape function that now characterizes so much of Australia's inland, but a host of other far-reaching and irreversible effects that could stop any attempts at restoration in future.

Marsupials also provide excellent opportunities for us to learn about ecology, behaviour, physiology, genetics, evolution and the development of the Australian environment. Because they represent an alternative path in mammalian evolution, marsupials also present unique insights for biomedical researchers. Currently, we use marsupials to understand the development of the immune, the reproductive and the nervous systems. We use them to study the determination of sex in the young, mechanisms for the repair of DNA and for the processing of cholesterol and other dietary fats, and even how to cope with stress. We are extracting compounds from their milk to overcome bacteria that have become resistant to our standard antibiotics, and we are sequencing their genetic code to probe the origins of genetic diseases. As beacons for overseas visitors, marsupials contribute enormously to the national economy.

But all is not well in the world of marsupials. Since the arrival of European settlers in 1788, Australia has lost 11 of its original 160 marsupials. Many more face the risk of extinction. What is the future for Australia's flagship mammals?

A pessimistic view might say 'game over'. Recent research suggests that species that have been around for a long time are more prone to extinction than recently evolved models, perhaps because they breed slowly or become too specialized to cope with environmental change. The marsupial moles, rainforest possums and the western Australian numbat fit this category. Then there is the looming spectre of climate change. Cold-loving species such as the beautiful mountain pygmy-possum and Leadbeater's possum will have little habitat left in the hothouse to come and so must walk the world as zombies until their time is up. Longer droughts, flooding rains and more intense wildfires will put other species at risk. If we take the pessimistic view to its extreme and assume that the 34 species of living but threatened marsupials in Australia will fall by the wayside, the continent will be impoverished indeed.

A more moderate view is that the status quo will be maintained. We still clear the land and view some marsupials as pests, and as a nation do not accord the environment with enough respect. But we also conserve marsupials in small protected areas and recognize them under legislation. Conservation organizations are flourishing, and have replaced the advocates who once called for marsupial destruction. With diligence and action, we may yet be able to maintain the fragile balance between judicious conservation and rampant development.

The most optimistic view is that more Australians will learn to appreciate the environment, and overcome their ambivalence about the fate of the marsupials and other unique animals and plants that it sustains. This could happen if we teach our children a sense of place, if we show more clearly why marsupials and their habitats are valuable and important, and if we understand the terrible consequences and finality of extinction. It could also happen if we better inform different levels of government so that political decisions about the environment are not made in ignorance of marsupials and other natural resources, but with due regard for their interests against the competing demands of developers and economic rationalists.

I think there are signs of progress, but in reality, dear listener, it's you who will decide which view prevails.


Professor Christopher Dickman  

School of Biological Sciences 

University of Sydney