Morphophenetic analysis of American mink (Neovison vison) populations from the Caspian-Baltic watershed

Abstract

The morphological variability of 367 skulls of the American mink from Tver, Pskov, and Novgorod oblasts (Caspian-Baltic watershed) are investigated using quantitative and qualitative traits. Out of the six investigated samplings, five represent feral populations and one represents ranch minks. It is shown that significant morphological differences between feral mink populations exist within a relatively small area (about 250 × 350 km). Differences in the phenotype are determined by different history of the populations and by the degree of affection of escaped ranch animals. The possible consequences of interactions between the feral and ranch mink populations, which may influence the phenotype, are discussed. The morphological differences observed between the feral mink populations are lower than those theoretically expected when taking into account the considerable influence of domesticated animals. Among the possible reasons of morphological stability of skulls of feral populations of the American mink, we specify naturalization of sizes of ranch escapees under pressure of environmental conditions, as well as possible elimination of the first-generation hybrids between feral and domesticated minks owing to outbreeding depression.