Assessment of genetic variability in captive and wild American mink (Mustela vison) using microsatellite markers

The genetic variability of 212 black mink from four ranches, and 20 each from wild mink trapped in Eastern Canada, pastel and brown (wild-type) was assessed using seven microsatellite loci. The average number of alleles per locus and expected heterozygosity (H-E) in the entire sample were 6.57 and 0.63, respectively. The estimates of H-E were comparable among the black mink herds (0.53 to 0.61), and between black and the wild mink (0.50), indicating a considerable level of genetic variability within black mink, despite high levels of uniformity that have been achieved in fur quality traits as a result of many years of intense selection. Brown mink had the highest HE among populations (0.65), which could be the cause or the effect of their higher vigor and reproductive performance compared with the black mink. All the populations showed a higher level of homozygosity than expected from the Hardy-Weinberg (H-W) proportions at several loci (positive F-IS), perhaps as a result of linebreeding and positive assortative mating commonly used in the mink industry. Excess of homozygosity in the wild mink may indicate breeding between related individuals occupying adjacent territories, and a limited movement of mink in the wild. The black mink herds were closely related to each other, as were the pastel and brown. Gene flow from common sources to ail the herds and infusion of the Jetblack allele into all the ranches were likely the causes of relatedness of the black mink herds. The black mink herds were more closely related to the wild mink than to the colored mink. This panel of microsatellites correctly classified black and nonblack mink into their respective groups with 91 to 97% accuracy. Between 70 and 88% of the black mink were correctly assigned into their herd of origin.