I’ve come to visit them on a blinding hot February day, and I’ve been excited about the encounter for weeks. But when I open the door and see them, squatting blithely in row upon row of plastic tanks, I’m struck with a potent wave of tragedy.
These are juvenile southern corroboree frogs, tiny little things with an overlaid pattern of bright yellow and black on their breathable skin, like a croaking nuclear waste sign. That’s pertinent, because they secrete a poisonous alkaloid through that skin that can kill prospective predators.
I squat on my haunches, greeting one of the little frogs as it hovers, suction-cup toe-pads pressed against the glass, its little throat moving rhythmically up and down. It has no idea what’s coming.
These young frogs, some no bigger than the tip of my thumb, are doomed – they won’t live for more than a few months at most. But their deaths may be the key to reversing the march of their species towards extinction.
That’s because these frogs are the first test subjects in a project that will plumb some of the most exciting (and controversial) realms of science, in the quest to conserve a dying species – by striding into the vanguard of gene editing.
Lee Berger was in the midst of her PhD at James Cook University in the 1990s when she began investigating an alarming and inexplicable global decline in amphibian populations that had been going on for at least 20 years. At the time, its effects were seen most acutely in the rainforests of Central America and Queensland.
Mass frog deaths were moving across the landscape, following the kinds of patterns you expect from an epidemic, and researchers were proposing that some sort of exotic pathogen must be behind the deaths. But it was Berger who, in 1998, first identified a fungus, Batrachochytrium dendrobatidis, suffusing the skin of sick frogs.
Southern corroboree frogs are native to the mossy sphagnum bogs of the northern Snowy Mountains, and are exclusively found within the limits of Kosciuszko National Park. They summer in mossy chambers, where the males voice a charmingly offbeat ‘squelch’ to attract their mates. In the winter, they retreat to the snow-sheltered undersides of snow-gum logs and leaf litter.
Southern corroborees are now functionally extinct in the wild, because B. dendrobatidis causes a ravaging disease known as chytridiomycosis. According to Zoos Victoria, there may be fewer than 50 of these frogs left in their natural habitat, and the tiny group remaining only persists because breeding programs have periodically replenished their dwindling population.
, also known as the chytrid fungus, takes advantage of amphibians’ most important evolutionary quirk – their porous skin. “Frogs actually absorb oxygen through their skin,
