In the 12th century, the rabbit was brought to England from southern Europe by the Normans. They were kept in captivity in warrens as a source of meat and fur. Eventually some escaped into the wild and eventually became so common that farming them was no longer economical.
During the 1800s, British settlers in Australia just couldn't bond with the native koalas and kangaroos, so they starting importing familiar animals from Britain.
In 1859, a landowner in Northern Australia released a number of wild European rabbits into the environment. At the time, it seemed like a good idea since it provided food and good hunting.
However, the habitat was ideal and there were no natural predators to control the rabbits. They soon established a large population that displaced livestock — even kangaroos — by overgrazing perennial grasses during good weather and stripping bark from shrubs and trees during droughts. They transformed grasslands and scrublands into eroded deserts.
There ensued an all out effort to try and eradicate this pest using all kinds of methods. Even a 2,000-mile-long fence was built to protect Eastern Australia from this invasion, but rabbits made it to the other side before the fence was even completed.
In 1951, government scientists introduced myxoma virus obtained from South American rabbits into the rabbit population. It is transmitted by biting insects and causes a disease called myxomatosis. The disease has only a mild effect on the South American rabbits where it originated and co-evolved with the local rabbits.
However, this virus had a very lethal effect on European rabbits that had never been exposed to this pathogen. The Australian rabbits died in droves for a period of several years until a few rabbits, whose genotype provided resistance to the virus, were able to replenish the population with some resistant rabbits. The mortality rate dropped to approximately 25 percent compared to 90 percent when the virus was first introduced. In addition, the virus became less lethal due to mutations it produced in order to survive and be transmitted in its new environment. To this day, rabbits are still a major pest problem in Australia.
Larrie Stone is a retired Dana College science professor.