Picture credits: Trustees of the Natural History Museum
An unprecedented study of rabbit DNA spanning 150 years and thousands of miles has revealed the genetic basis for the animal’s fightback against the deadly myxoma virus. Using the latest technology, an international team including Kings, the University of Cambridge and CIBIO Institute in Porto, extracted DNA from nearly 200 rabbits dating from 1865–2013, including one owned by Charles Darwin. The scientists then sequenced nearly 20,000 genes to pinpoint mutations that have emerged since the myxomatosis pandemics of the 1950s.
The study, published today in the journal Science, establishes that modern rabbits in Australia, the UK and France have acquired resistance to myxomatosis through the same genetic changes. The scientists also discovered that this resistance relies on the cumulative impact of multiple mutations of different genes.
Australia unleashed myxomatosis on an out-of-control rabbit population in 1950. The European rabbit is thought to have been introduced to the country by Thomas Austin, an English settler, in the 1850s. Within a century, they numbered hundreds of millions. The species wreaked havoc on Australia’s native plants and animals but in less than three months, myxomatosis had spread 2,000 km and killed 99 per cent of infected animals. In 1952, the virus was illegally introduced in France and in 1953 it reached the UK, leading to similarly devastating results in both countries.
Scientists soon began tracking the evolution of both the virus and the rabbits, and in all three countries, they observed a substantial drop in fatality rates. They concluded that this was due to the disease becoming less virulent but also rabbits becoming more resistant. Animal populations exhibit considerable genetic variation in susceptibility to infection which allows for rapid evolution of resistance when exposed to new diseases. The pandemics of the 1950s triggered a particularly intense process of natural selection. Those initial findings have become a textbook example of host-parasite coevolution but this new study offers a far more detailed picture of what has been happening in rabbits.
Historical samples from 11 natural history museums were collected, in the UK, France, Australia and the United States. One of the rabbits from which DNA was sequenced belonged to Charles Darwin and is now housed in London’s Natural History Museum.