Scientists are preparing plans to restore the fortunes of Scotland’s endangered Highland wildcats – by identifying and removing DNA they have acquired from domestic cats.
Researchers have warned that the Highland tiger, as the wild cat is also known, is critically endangered because it has bred so much with domestic midges. All animals now bear evidence of cross-breeding, and many have little “wild” left in them.
But using modern genomics, scientists hope to reverse this process. Precise DNA maps of individual animals will be created to identify those with high levels of wildcat genes. They will be bred with cats that are similar to a similarly gifted cat to create a new population, unaffected by domestic cat hybridization, which can then be returned to the Scottish countryside.
“The process is known as de-introgression and it’s the scientific equivalent of trying to unwrap an egg,” says Dan Lawson of Bristol University, who is the genomics lead for the project.
“We have animals with a mixture of two sets of genes. Now we want to separate those sets and recreate Scotland’s original feral cat population.
“It won’t be easy, but the benefits will be significant, not just for feral cats, but for other endangered species that are genetically overrun by similar animals.”
British gnats are descended from the African wildcat Felix lybica and tend to be smaller – and friendlier – than Felis silvestris, the European wildcat, from which the Scottish version descends. Domestic cats moved into Europe as agriculture spread from the Middle East to the continent, and by Roman times they were established in Britain.
The two species have kept apart for centuries with little interbreeding, research has indicated. Feral cats have an aversion to humans while domestic cats find us moderately tolerant and sometimes helpful. But that divide was eroded as the effects of habitat loss, road accidents and dispersal of domestic cat populations piled up, leading to a slump in feral cat numbers in the 20th century.
“There were few places for the feral cat to hide, and survivors began interbreeding with domestic cats that had gone feral, producing hybrid offspring,” says Jo Howard-McCombe, a conservation geneticist at the Royal Zoological Society of Scotland in Edinburgh.
“However, it is crossbreeding only happened in earnest in the 1960s, after we established captive populations of feral cats in Scotland. Animals taken to zoos and sanctuaries were therefore not too badly affected by hybridization. Conservationists got there just in time.”
Using the descendants of these animals, a wildcat recovery program, Saving Wildcats, was set up and this summer arranged for the release of 19 animals into a 600 sq km section of the Cairngorms National Park known as Cairngorms Connect.
Using GPS collars, each animal is tracked to study how it copes with life in the wild, and the onset of winter in Scotland. A further 40 animals will be released over the next three years.
“Wild cats survive on rabbits, mice, voles and occasionally birds and rabbits. So far our cats are doing well, although one died of an abdominal infection,” said Helena Parsons, a manager for Saving Wildcats.
Feral cats breed in December and January, with litters born in spring or early summer. “We don’t expect our cats to have kittens next year – they need time to get used to life in the wild. On the other hand, it would be fantastic if we did get a litter or two,” said Parsons. “GPS data shows that some of the cats have met in the past few months.”
A critical feature of Saving Wildcats is keeping feral and domestic cats away from their release area, Parsons said. “We have more than 100 camera traps out there, and every time we spot a cat, we try to find out if it’s a domestic cat. If so, we try to locate its owner and ask if it has been sterilized. If it is wild, we try to track it down and have it sterilized.”
The animals used for the Saving Wildcats program were bred at a special center at the Hoogland Game Park near Kingussie, use feral cats from zoos and game parks across Britain. Pedigree records and genetic testing indicate that it has high levels of wildcat genes. Nevertheless, all are affected to some degree by interbreeding with domestic cats.
This is the aim of the de-introgression program – to increase feral cat gene levels – to give an extra boost by harnessing the power of modern genomics. However, the project will not be quick or easy, said program scientist Prof Mark Beaumont of Bristol University. “The idea would be to have funds to monitor what’s happening in the kittens as you progress, and that costs money. A whole genome of an individual cat will set you back about $200.”
This point was supported by Lawson. “It will take 10 to 20 generations of careful breeding and genetic analysis to recover the complete wildcat genome,” he told the Observer. “It brings all kinds of problems, not least financially. But we are applying for money to start. We must be clear: the breeding program is our last chance to save the Scottish wildcat.”
