A conservation success story: the European Polecat

A close relative of the ferret (Mustela putorius furo), the European polecat is set to thrive in mainland Britain after its re-emergence, in contrast to its current declining population across the continent. Known to cross-breed with domestic ferrets, our scientists are working to identify the degree of hybridisation between the domestic ferret and European Polecat to further support the Polecat species. Dr Graham Etherington from the Di Palma Group (Vertebrate & Health Genomics) explains further.

Even by the start of World War 1, the European Polecat had been persecuted so much that it had disappeared almost completely from England and Scotland, with only a small isolated population remaining in Wales.

At the same time, domestic ferrets escaped and formed a number of feral populations. Since then, the European Polecat has expanded its range and is now found across much of The Midlands, East Anglia, Cumbria, the south-west and other places.

Evolutionary adaptation drives biodiversity, therefore, genetic variation is key in sustaining a species’ resilience and longevity when facing changes to their habitats due to environmental change, human intervention and invasive species.

A flailing population and absence of gene flow can have a detrimental effect on a species’ genetic diversity, reproductive ability, and their adaption to environmental change; increasing the risk of extinction. Our research findings will help us comprehend how evolutionary pressure shapes the DNA make-up in natural populations such as the European Polecat and the impact on their ecosystem.

During the range expansion, European Polecats have hybridised with domestic ferrets, but the extent of this hybridisation is unknown. Here at EI, we’re particularly interested in genome introgression - the movement of genes from one species to another, in this case, the introgression of feral ferret genes into the European Polecat genome.

From focusing on genome introgression, we want to see if we can find parts of the domestic ferret genome present in polecat genomes and to what degree this introgression occurs. We can then see if these genes contain beneficial characteristics, which allow polecats to be more successful at hunting, breeding, co-existing with humans, etc.

By sequencing the genomes of British European Polecats, we can make side-by-side comparisons to the genomes of domestic ferrets and non-British European Polecats. From this, we should be able to see the parts of the genome that are more similar to the ferret genome and those that are more similar to the polecats. We can then create molecular tools that conservation biologists can utilise to quickly and cheaply identify the amount of introgression in large samples of European Polecats.

Dr Etherington goes on to say: “Previously deemed as a pest, conservation attitudes towards the European Polecat have altered; people are more aware of their surroundings and the importance of balanced eco-systems. Endangered species are now also protected by law and although that’s no guarantee to not be persecuted by over-zealous gamekeepers and alike, it certainly makes the public more sensitive to wildlife issues and their own livestock.

If you’re a British polecat, the future looks quite bright. Whether it be due to rejuvenated habitat, wildlife protection laws, genetic influences, or a combination of all. With a range expansion - east to Norfolk and Kent, south to Cornwall and north to the Scottish Borders - British polecats are a conservation success story.”

Prof Federica Di Palma, Director of Science at EI, added: “This is one of our most exciting projects that gives us the opportunity to understand the impact of genetic diversity in domestication, inbreeding depression and wildlife management”.

To find out more about the work towards the national conservation of polecats, monitoring the species’ expansion range, visit the Vincent Wildlife Trust website.

Being restricted to the UK mainland means that many British mammals are slightly different to those found on the European continent.

Isolation (from Europe), evolution and selection over time means that the British European Polecats follow their own evolutionary path, distinct from that of its European counterpart. If we lose the British population, we lose a unique population that can never be replaced.

Following the UK Government’s wildlife protection guidance, Group Leader at EI Wilfried Haerty, who has previously studied the ecology of the polecat and its feeding behaviour in Luxemburg, thinks the European Polecat’s expansion in the UK and decline in Europe is due to the species habitat protection.

“In Europe, the decline of the polecat is directly related to the loss of habitat including the disappearance of some of its preys (small rodents, amphibians). The protection of the polecat and landscape protection (Wildlife and Countryside Act, for instance) should have been the major factors explaining the recovery in the UK. However, this would explain only a relatively recent recovery.

In parallel, the same situation has been observed in the UK for the European Otter, covered mostly because of environment policies (pesticide bans and habitat protection).

“For the polecat, I think the most important factors are the measures taken around this species with the preservation of its habitat which should have been beneficial to many other species such as many amphibians (frog, toads and newts) that are directly threatened by the degradation of their habitat. I think this side effect can be generalised to many of the species that are currently actively protected with a recovery programme.”