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 19th 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.