[Post 5] Ferret-polecat hybrids

Ferret-polecat hybrids

The two specimens to the far left are hybrids, the three to the right are pure polecats.

Ferrets (Mustela putorius furo) and European polecats (Mustela putorius) are both in the Genus mustela, which also contains weasels and mink.  Ferrets are domesticated animals (domesticated circa. 2,000 years ago) and are often kept as pets. Often species escape captivity and some can survive and establish self-sustaining populations in the wild, independent of their previous owners. This is likely to have happened with ferrets. It has been noted that feral ferrets are breeding with wild polecats. 

In the 19^th century, polecats declined in number due to persecution from gamekeepers. Since this time, polecat populations have been expanding, however introgressive hybridisation with ferrets has become a significant conservation issue. The wild polecats have certain traits that assist their survival, which are determined by their genes. When ferrets mate with polecats, the polecat’s genes are diluted, therefore affecting their well-adapted traits. By genetically ‘polluting’ the polecat population with ferret genes, the fitness of the hybrids can be affected. However, it is has been suggested that hybridisation with ferrets may actually have played a part in the recovery and increase in polecat population size, but it is still not fully understood.

Hybridisation may be beneficial for the population size, however, conservation policy can be confused over who to conserve, as genetic integrity of the polecat is compromised by ferrets. Conservation is now focused in the regions home to the purest polecats in the UK and further work aims to minimise the escape of captive ferrets. By focusing efforts on the purebreds, conservationists hope that the species will expand their range and begin to reverse the effect of introgressive hybridisation.

Specimens to the left are ferret-polecat hybrids, to the right are pure polecats. Markings are different between the two, the hybrids generally have a larger body size with more white fur along the back. Pure pole cats have a more white underside to the head compared to ferrets. These taxidermy specimens are located in the World Museum, Liverpool.