19th century farmer may be to blame for Australia’s rabbit plague | Science

On Christmas Day 1859, a shipment of 24 rabbits arrived in Melbourne, Australia, from England. The bunnies were a gift to Thomas Austen, a wealthy English settler who aimed to establish a colony of the creatures on his Australian estate. He accomplished that—and then some.

Just 3 years later, thousands of his European rabbits (Oryctolagus cuniculus) were jumping around. By 1865, Austen would boast to the local newspaper that he had killed around 20,000 rabbits on his property, where he hosted rabbit hunting parties for English royalty such as Queen Victoria’s son, Prince Alfred.

Austin wasn’t the first person to bring rabbits Down Under. Five of the animals were on board the first flotilla of British ships to reach Sydney in 1788, the start of approximately 90 introductions of rabbits along Australia’s east coast over the next 70 years. Yet it was Austin’s bunnies that dominated the continent, a new study finds. An estimated 200 million rabbits now wreak havoc on crops and native plants, causing $200 million a year in agricultural damage. And almost all of them, the researchers conclude, can be traced back to the fateful shipment Austin received in 1859.

To figure out how rabbit plague started, Francis Jiggins, a geneticist at the University of Cambridge, and his colleagues analyzed the genetics of 187 specimens of rabbits collected in Australia. They also tested potential source populations in England and France and a handful of rabbits from Tasmania and New Zealand, places that have experienced their own devastating rabbit invasions.

Most of Australia’s rabbits, apart from two localized contingents around Sydney, shared a common ancestry, the team reported today in Proceedings of the National Academy of Sciences. The rabbit genomes also revealed that the epicenter of the invasion was near Austin’s estate in Victoria. As the rabbits spread further away from the site, the population becomes less genetically diverse, resulting in a homogenous horde of rabbits. What’s more, the researchers found several genetic similarities between Australian rabbits and bunnies in southwest England, where the Austin family collected the first batch of rabbits to ship to Australia. The researchers conclude that Australia’s ongoing rabbit plague began when Austin let the initial shipment of 24 rabbits loose on his estate.

Genetics provided clues as to why this population was primed for invasion. Accounts of earlier Australian rabbits mention pendulous ears and beautiful colored fur, two traits common in domesticated rabbits, suggesting that they may have been too domesticated to adapt to Australia’s wild landscape. But the Australian rabbits descended from Austin’s offspring had a large amount of wild ancestry, the genetic analysis revealed.

An 1888 monograph by Thomas Austen, the English settler who introduced a batch of rabbits to his Australian estate in VictoriaBritish Library

The historical record supports this. Austen family letters and lore reveal that Austen’s brother sent several wild rabbits in addition to the domesticated ones to Australia. The rabbits began interbreeding during the 80-day boat trip.

Austin’s rabbits had another advantage over their predecessors: they arrived in a more forgiving Australian environment. When the earlier newcomer rabbits ventured out into the bush, they encountered strange plants and a host of carnivorous reptiles, marsupials and dingoes. But by the mid-19th century, the wasteland was converted to pasture and predators were hunted to protect livestock. “It was like a perfect storm,” says co-author Joel Alves, an evolutionary geneticist at the University of Oxford.

Australia’s landscape is still struggling with the effects of this storm. After the rabbits hopped outside Austin’s estate, they spread more than 100 kilometers a year despite fences and strains of smallpox-like viruses designed to destroy them. In just 50 years, the animals have colonized an area roughly 13 times larger than their native European range, a rate faster than any other introduced mammal, including pigs and cats.

And they continue to multiply. “It’s like a faulty brake on a car,” says Alves.

However, not all scientists blame Austin alone for Australia’s rabbit plague. David Peacock, an ecologist at the University of Adelaide, said other rabbits were released on the continent around the same time as Austin’s. In 2018, Peacock co-authored a study arguing that the rabbit invasion was caused by multiple rabbit introductions.

But he welcomed efforts to unravel the origins of Australian rabbits, saying they could aid efforts to create more targeted pathogens to control and potentially eradicate rabbit populations. “That much better [we understand] origins, distribution and genetics, the better we can manage Australia’s most serious pests.”

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