DNA profiling solves Australian rabbit plague puzzle

Rabbits were first introduced to mainland Australia when five pets were brought to Sydney on the First Fleet in 1788. At least 90 subsequent imports would be made before 1859, but none of these populations has become invasive. But within 50 years, at the rate of 100 km per year, the rabbits would spread across the continent, making it the fastest colonization rate ever recorded for an introduced mammal. So what changed after 1859 and how did the invasion start?

Historians and the Australian public have long assumed that the country’s ‘rabbit plague’ began in Barwon Park, Thomas Austin’s estate, near Geelong in Victoria. In a study published today in PNAS, an international team led by the University of Cambridge and the CIBIO Institute in Portugal finally provides genetic evidence for this version of events and settles a debate about whether the invasion was born from a single or several independent introductions.

October 6 1859, Austin’s brother, William, sent a cargo of wild rabbits – captured on family land at Baltonsborough in Somerset – as well as domestic rabbits, on the ship Lightning. On Christmas Day, rabbits arrived in Melbourne and were sent to Barwon Park. In three years, the “Austin rabbits” have multiplied by the thousands, according to a write-up of a community newspaper and Austin himself.

Researchers have studied historical records alongside new genetic data collected from 187 “European rabbits” – mostly wild-caught in Australia, Tasmania, New Zealand, Great Britain and France between 1865 and 2018 – to determine where the invasive rabbits came from. Australia whether the invasion resulted from a single or multiple introductions how they spread across the country and whether there was a genetic explanation for their success compared to that of other imported rabbit populations.

Recent studies have challenged the distinctive origin hypothesis, claiming instead that invasive rabbits resulted from multiple independent introductions. However, they did not sample ancestral European and domestic populations, which was important in unraveling the source of Australian rabbits. Lead author Dr Joel Alves, who is currently a researcher at the University of Oxford and the CIBIO Institute, said:

“We have managed to trace the ancestry of the invading population from Australia to South West England, where Austin’s family collected the rabbits in 200.

“Our results show that despite numerous introductions across Australia, it was a single batch of English rabbits that triggered this devastating biological invasion, the effects of which are still being felt today.”

Researchers found that as the rabbits moved away from Barwon Park, genetic diversity decreased and rare genetic variants that occur in rapidly growing populations became more frequent. rabbits, the deliberate introduction of myxoma virus and other measures, rabbits remain one of the major invasive species in Australia, threatening native flora and fauna and costing the agricultural sector approximately 200 million dollars per year.

Previous studies have suggested that several factors contribute to biological invasions, including the number of individuals, the number of introductions, and environmental changes. The new findings suggest that the genetic makeup of these animals may be just, if not more, influential.

The researchers point out that if the trigger for the invasion had been an environmental change, such as the development of large pastoral areas by human settlers, several local populations of rabbits would likely have developed. The study’s genetic findings and the failure of pre-rabbits 1859 to become invasive undermined this possibility.

Instead, the team explored the possibility that the arrival of specific genetic attributes acted as a trigger for the invasion, which would help explain the overwhelming genetic evidence from a single introduction.

Rabbits introduced to Australia before 1859 were often described as displaying docility, fanciful coat colors, and droopy ears, features associated with domestic breeds but normally absent in wild animals. Austin rabbits were described as wild-caught at the time, and genetic findings from the new study prove that at least some of these animals were indeed wild.

Lead author Professor Francis Jiggins from Cambridge’s Department of Genetics said:

“There are many features that could make wild domestic rabbits unsuitable to survive in the wild, but they may not have the genetic variation to adapt to Australia’s arid and semi-arid climate.

“To cope with this, Australian rabbits have evolved body shape changes to help control their temperature. It is therefore likely that Thomas Austin’s wild rabbits and their offspring had a genetic advantage to adapt to these situations.

At 20th century, Joan Palmer recalled that her grandfather William Austin had had difficulty procuring the animals for Thomas “because or truck wild rabbits were not by no means common around Baltonsborough. It was only with great difficulty that he managed to obtain 6 of them; they were half-adult specimens taken from their nests and tamed. To complete the number, he bought seven gray rabbits which the villagers had kept in hutches, either as pets or to eat.”

Alves and Jiggins discovered that the invasive rabbits from the Austin imports contained a substantial element of national ancestry which they claim supports Joan Palmer’s claim that the wild and domestic rabbits on the expedition bred before or during their voyage from 90 days, which would explain why more rabbits arrived than sent.

The Dr Alves said: “These findings are important because biological invasions are a major threat to global biodiversity and if you want to prevent them you need to understand what makes them successful.”

“Environmental change may have made Australia vulnerable to invasion, but it’s the genetic makeup of a little lapi good deal savage ns that unleashed one of the most iconic biological invasions of all time.”

“It reminds us that the actions of a single person, or a few people , can have a devastating affect on the environment.”

Related Articles

Back to top button