Separating wild from domestic American mink Neovison vison based on skull morphometrics

Domestication can change animal traits such as skull size and shape. Given that domestic American mink Neovison vison may escape from farms within the native range of wild mink, we were interested in determining whether 1) skull characteristics differed between wild and domestic mink, and 2) free ranging mink in Ontario had skull features characteristic of domestic animals. Contrary to previous research, we found no effect of domestication on braincase volume or muzzle length in mink. We did, however, find that skulls of domestic mink were larger than those of wild mink and that domestic skulls had narrowed postorbital constrictions (POC). A model using both condylobasal length (CBL) and POC correctly classified the origin of 100% of male skulls and 90% of female skulls in an external data set. A POC-only model was less successful, however, correctly classifying 68% and 70% of male and female skulls, respectively. In a field application of the two-term model, only one of 109 skulls was identifed as being of farm origin. With the POC-only model, however, 12 skulls were classified as being from domestic animals. Where size differences are expected (for example, with recently escaped animals), the model should be effective for identifying domestic mink. However, the utility of CBL and POC for identifying domestic-origin or hybrid animals that have been born in the wild depends oil a key uncertainty, namely, the extent to which these traits have a genetic basis.