Davison, A. et al. (1999). Hybridization and the phylogenetic relationship between polecats and domestic ferrets in Britain

Ferrets were domesticated from polecats more than 2000 years ago. Following their introduction to Britain, they escaped and hybridized with native European polecats. Native polecats declined to the point of near extinction prior to World War I but have recently begun to expand from a Welsh refugium. Concern has arisen as to the extent of polecat/ferret introgression, and in particular, whether the expanding population is of mainly hybrid origin.