Winning and Losing: Rabbits versus Virus


Invasive rabbit eating invasive rabbit-resistant plant in Australia (photo from Wikimedia Commons)

You would not think that something this cute could be a problem but European rabbits (Oryctolagus cuniculus) have plagued Australia for 160 years. After a century of recurring population explosions (think “plagues of locusts”!) scientists found a virus that kills only European rabbits. They introduced it in 1950 and it worked amazingly well for a while but the rabbit and the virus both evolved. Here’s their story.

Introduced for hunting in Geelong, Australia in 1859, the European rabbit immediately went feral and the population went out of control. Without any predators they covered most of the continent by 1910.

Range of the European rabbit; pink means “Introduced” (map from Wikimedia Commons)

Periodic population explosions, called rabbit plagues, became the norm. The rabbits eat everything. They devastate native plants, push out native animals, denude the countryside and cause dust bowls. In the photo below, at dusk, they are everywhere but probably not a plague yet since there’s still some grass.

So many rabbit holes. No trees or shrubs (photo from Wikimedia Commons)

Hunting and poisoning were ineffective.

Then in 1950 scientists found a virus in South America, called myxoma, that killed European rabbits. They released it in Australia (and in France) and it cut the rabbit population by 99%. Wow!

But a few rabbits lived and so did the virus. Science Magazine reports that “within a decade, rabbit numbers were on the rise again as some evolved resistance to this deadly infection and the virus itself became less deadly.”

This month, a new DNA study of both the rabbit and the virus shows that:

Rabbits on two continents evolved the same genetic changes to beat back the virus—before the virus itself changed and regained the upper hand. […and…] In the 1970s the virus developed a greater ability to suppress the rabbit’s immune responses. That change, as well as the natural emergence of another rabbit-killing virus, has caused populations to decline again.

— Science magazine, 14 February 2019

The arms race continues.

Don’t worry about the rabbits. They had another population explosion in 2004. At last count there are about 200,000,000 of them in Australia.

After all, they breed like rabbits.

For more information, read “Seventy years ago, humans unleashed a killer virus on rabbits. Here’s how they beat it” by Elizabeth Pennisi in Science Magazine.

(photos and range map from Wikimedia Commons. click on the captions to see the originals)