Mink gone wild: Hybridization between escaped farm and wild American mink (Neovison vison) in a natural context.

摘要

The release of cultured organisms into natural populations may adversely affect the population through predation, resource competition and disease introduction. Of even greater concern is the potential for hybridization between wild and farmed conspecifics, which may alter the evolutionary integrity of the infused populations. Wild American mink (Neovison vision) populations may be threatened not only by the presence of domestic mink originating from farms in Canada, but by breeding with such escapees. Using 10 microsatellite loci I genotyped mink sampled from two farms, two putatively mixed populations in regions surrounding the mink farms and two from wild populations with no history of farming in the region. Genotypes were employed in Bayesian population assignment. I identified four population clusters, including one wild, and three farmed populations. The latter were not clustered by farm but rather by distinct line-bred colour phases. Population clustering further identified farmed and hybrid mink in the wild populations. Over 50% of the mink sampled in the populations in close proximity to mink farms (81% and 43%) were either farm escapees or descendants of escapees. Analysis of body mass and length of mink indicated that the hybrid individuals were intermediate in size to the relatively small wild and the large farmed mink. However, behavioural comparisons showed no differences between farm and wild mink, possibly because of a lack of statistical power due to low numbers of true wild mink determined after population assignment. The colour of the wild caught animals was 92.5% concordant with the genetic population assignment. The overwhelming presence of farmed animals and their hybridization with wild mink in natural populations is a great concern for the future sustainability of mink. I suggest that the province should maintain a relationship with mink farms, either through licensing or assessment of biosecurity standards.