The Best Australian Science Writing 2013 (36 page)

Australia's first extinction wave started to gather pace almost as soon as the First Fleeters stepped ashore, and by the 1940s it had carried away 10 per cent of the continent's mammal species. No other class of organisms has suffered so grievously, and
as a result mammals have become something of a yardstick by which we measure our long-term environmental impact. In 1791 a convict wrote about the white-footed rabbit rat, saying that it was a pest in the colony's food stores. The soft-furred, grey and white kitten-sized creature was arguably the most beautiful of Australia's seventy-odd native rodent species, yet it was destined to be one of the earliest victims of European settlement. Two hundred years ago it could be found in woodlands from near Brisbane to Adelaide, but the last record of it dates to the 1850s. Because foxes and rabbits had not begun to spread by this time, it is thought that a major factor contributing to its extinction was the end of Aboriginal fire management.

The thylacine and the toolache wallaby were the largest creatures to succumb in the first extinction wave. Both had small populations and restricted distributions (Tasmania and the southeast of South Australia respectively), and are unique in being the only species that were hunted to extinction by Europeans. The thylacine was Australia's largest marsupial carnivore and, being wolf-like in appearance, it was persecuted by sheep farmers, the bounty on its head outlasting the creature itself. The beautiful toolache (pronounced ‘toolaitch') wallaby had the misfortune of being the fleetest member of the kangaroo family, and so was hunted to extinction for sport. These extinctions were, however, atypical: indeed, one of the most astonishing aspects of the first extinction wave was that its victims included what had been the most abundant and seemingly secure mammals in Australia.

Among the victims that once abounded were a dozen kittento hare-sized marsupials, mostly wallabies, rat-kangaroos and bandicoots, as well as nine species of native rodent. All of these species vanished between the 1840s and the 1930s, and all inhabited southern and central Australia. Strangely, many remained common until the moment of their vanishing. For example, according to the pioneering zoologist Frederic Wood-Jones, in
the early years of the 20th century in Adelaide the rabbit-sized marsupials known locally as ‘tungoos' (brush-tailed bettongs and their relatives) were sold at nine pence per dozen for greyhounds to chase and kill. Yet just a few years later they were only a memory, with not so much as a single skin remaining in the state's museum.

The causes of these extraordinary extinctions are thought to have been varied. The cessation of Aboriginal burning doubtless had its effect, and until the 1930s bounties were paid by many state governments for the scalps of now-extinct creatures. But the depredations of foxes (which were spreading quickly by the early 20th century) and feral cats, and the wholesale destruction of native vegetation by livestock and rabbits, must also have been important causes. While the causes are disputed, the effect of the first extinction wave is clear: it gutted the biodiversity of the drier parts of the continent, and very few native mammals larger than a rat and smaller than a kangaroo can be found on Australia's inland plains today. It's the absence of such species – the so-called critical-weight-range mammals (which weigh between 500 grams and 5 kilograms), which were once among the most abundant of creatures – that has led me to characterise the national parks of Australia's southern inland as ‘marsupial ghost towns'.

The gathering second extinction wave is now mopping up the few surviving medium-sized mammals in Australia's south and inland. It's not difficult to predict which will be the next to become extinct, for, like the pipistrelle, their decline has been charted for years. There are 15 frogs, 16 reptiles, 44 birds, 35 mammals and 531 plants on Australia's endangered species list, and among those closest to the brink are three mammals: the central rock rat, the bridled nailtail wallaby and the numbat. All hang by a thread, and with the single vexed exception of the saltwater crocodile, next to nothing effective is being done to halt their slide into oblivion.

The most dismaying aspect of the second extinction wave is that it is emptying vast swathes of the continent that were untouched by the first wave. Australia's Top End and Kimberley were, until recently, a paradise for medium-sized mammals, among them a close relative of the white-footed rabbit rat. The last two decades have seen this fauna all but exterminated in the Top End, even in our most valued and best resourced national parks.

Perhaps it is excusable that Australians are unaware of the extinctions currently occurring in distant places like Arnhem Land and other regions of our far north. But astonishingly, we also seem blind to the perils facing species much closer to home – for example, the sand flathead of Port Phillip Bay. A fish familiar to every Melburnian who has ever dangled a line, its population has declined by 97 per cent over the past decade. That means that just three fish survive for every 100 that were present in 2002. While the reasons for the decline are unclear and may be multiple, overfishing is clearly a factor. Yet many recreational fishermen still angrily refuse to countenance the development of a system of marine reserves extensive enough to give the species a chance. I've seen tinnies lined up like taxis at an airport cab rank along the edge of the pathetically small Ricketts Point Marine Sanctuary (just 115 hectares), hoping to hook one of the fish it shelters. Because fishing is prohibited in the sanctuary, the place is a haven for amazing creatures, including the Port Jackson sharks that have been eliminated elsewhere in the bay. It is a reminder of what an abundant marine environment Port Phillip Bay once was, and could be again under good management.

Why should the extinction of Australian organisms concern us? I've had people tell me: ‘I don't give a stuff about cute furry animals. What have they ever done for me?' The answer, I think, is almost precisely the same as to the question of why human rights are important, even when they concern people we'll never
meet. First and foremost, it is a matter of values. The demise of a bat may not weigh greatly in the balance of human wellbeing, but it speaks volumes about the human soul. Do we wish to be despoilers and executioners of the natural world? Or do we want our children to have the opportunity to enjoy a world as bountiful and diverse as the one our parents bequeathed to us?

Politics

The future

Alive as a dodo

Nicky Phillips

For more than 3 billion years since single-cell organisms first appeared on the planet, life has evolved in one direction only. When a plant or animal becomes extinct, there is no coming back. Or so we thought.

In early 2013 Australian scientists revealed they had reversed natural selection. Not only had the aptly named Lazarus Project group revived the genome of an extinct species, the gastric-brooding frog, they had also grown embryos containing the bizarre amphibian's DNA – the crucial first step in their attempt to resurrect a dead species.

The head of the team, University of New South Wales palaeontologist Mike Archer, announced the milestone at the TEDx-DeExtinction event in Washington in front of international peers pursuing the same goal with other long-dead creatures – the passenger pigeon, woolly mammoth and Spanish ibex.

What stands out about the Australian team, however, is the pace of their progress. While other groups are years, more likely decades, from achieving their goal, the Lazarus team could have a gastric-brooding frog hopping back to life in the next few years.

The precise motivation for reviving a species, a process some call de-extinction, differs among its revivers, but a central theme
exists. Aside from the ‘wow factor', Archer says, scientists hope their attempt to turn science fiction into reality will help conserve the world's ever-diminishing biodiversity.

Cloning technology could not only bring back extinct species, especially those vanquished by humans, it could also play a vital role in conserving critically threatened plants and animals living today.

‘If it is clear that we exterminated these species, then I think we've got a moral imperative to try to do something if we can,' Archer says.

As with all endeavours that challenge the natural order of things, de-extinction has critics. Some conservationists fear the ability to revive species from the dead will distract from efforts to rescue the vast number of living yet endangered creatures.

Others wonder what kind of environment awaits revived species. If the reason they went extinct in the first place still exists, would we be resurrecting plants and animals only to watch them endure the same fate?

Mike Tyler's first encounter with the gastric-brooding frog came in 1974 when he received a call from a pair of Queensland schoolboys who had collected a frog with a bizarre method of brooding its young.

Female gastric-brooders would swallow their fertilised eggs and transform their stomach into a uterus where the young would metamorphose from tadpoles into baby frogs.

Close to bursting, the mother would then regurgitate her offspring one by one.

‘My feeling was that we were looking at something remarkable,' Tyler, a herpetologist at the University of Adelaide, says.

Tales of the bizarre creature quickly sparked the interest of the medical fraternity, who looked to the species for insights on how to treat stomach disorders.

But, just as this interest peaked, the frog vanished from the
wild in 1979, mostly likely a victim of habitat destruction and the human-spread chytrid fungus that continues to decimate global frog populations today.

When the last two adult frogs Tyler raised in his laboratory died in 1983, the species officially became extinct.

Even though it would be years before scientists would attempt to clone a mammal, let alone an extinct species, Tyler had the foresight to preserve a gastric-brooding frog in his deep freezer.

‘I thought it was a very special creature. At least I'd have material other people could use in the future,' he says.

Forty years later, Tyler told Archer of his frozen specimen. Lazarus' resurrection could begin.

Over the past five years, the team's Monash University genetics specialists, Andrew French and Jitong Guo, have painstakingly inserted single cells containing the DNA of the frozen frog into hundreds of donor eggs from a distant relative, the great barred frog, whose DNA had been deactivated by UV light.

In the beginning, the single cell frog eggs ‘just sat there', Archer says. ‘But then, all of a sudden, one of the cells divided, and then it divided again, and again. There were a lot of highfives around the laboratory at that point,' he says.

The cloning technique, known as somatic nuclear cell transfer, was used in 2003 by Spanish scientists to resurrect a recently extinct native goat – it survived for 10 days – and was similar to the process used to clone Dolly the sheep.

In the lab, the Lazarus cells continued to divide into three-day-old embryos. But then they died.

Genetic tests revealed the embryos, known as blastulae, contained the DNA of the extinct frog so the team is confident their extinct genome is functioning.

‘We know not all embryos survive,' French says.

The quality of the donor egg, injecting the extinct DNA, even the jelly the cells are cultured in can influence their survival, he
says. ‘The planets just have to align on the day.'

While the team are yet to bring back the bizarre amphibian, their success so far can prevent other frogs from becoming extinct.

‘The project is much bigger than the gastric-brooding frog,' says Simon Clulow, the team's youngest member and expert frog wrangler from the University of Newcastle.

With each species that is extinguished from the planet, a little piece of diversity is lost forever.

But the story need not end there, Clulow says.

If the team succeeds in cloning a gastric-brooding frog using a close relative as a scaffold, it demonstrates cross-cloning one species with another is possible.

One of Clulow's greatest passions is advocating for a national gene bank, which stores the tissue of endangered species that could be used to prop up dwindling wild populations or, should the creature go the way of the dodo, allow it to be revived later.

‘This project provides irrefutable evidence that gene banking is valid,' he says.

But for University of Adelaide ecologist Corey Bradshaw, attempts to resurrect extinct animals detract from efforts to conserve critically endangered species because they fail to solve the drivers of extinction.

Species revived from a few specimens would contain little genetic diversity, making them vulnerable to future threats and at risk of becoming extinct all over again.

‘It's not solving the real problem,' Bradshaw says. ‘If we encourage this sort of behaviour it's a massive financial distraction.'

Clulow disagrees, saying the Lazarus Project was inexpensive compared with other scientific endeavours and the money was donated from entrepreneur and philanthropists such as Dick Smith and geneticist John Shine.