Hybridization and the phylogenetic relationship between polecats and domestic ferrets in Britain

Ferrets (Mustela furo) were domesticated from polecats (M. putorius, M. eve rsmannii) over 2000 years ago. Following their introduction to Britain, the y escaped and hybridized with native European polecats (M. putorius). Nativ e polecats declined to the point of near extinction prior to World War I, b ut have recently begun to expand from a Welsh refugium. Concern has arisen as to the extent of polecat/ferret introgression, and in particular, whethe r the expanding population is of mainly hybrid origin. Therefore, mitochond rial DNA sequencing was used to investigate polecat genetic diversity in Br itain. Two geographically distinct lineages were found, where one may be an cestral to the British polecat, and the other to the domestic ferret. The a ncestral distribution of each lineage, or assortative mating is sufficient to explain the observed pattern. A further comparison between the distribut ion of the polecat phenotype and mitochondrial haplotype implies that the c urrent population expansion may be mediated by dispersing male polecats hyb ridizing with female feral ferrets. However, the wild source of the ferret remains obscure. Relatively recent speciation from European mink (M. lutreo la) and black-footed ferrets (M. nigripes), and/or the effects of hybridiza tion result in an unresolved molecular phylogeny. (C) 1998 Elsevier Science Ltd. All rights reserved.