Can skull morphology-morphometry discern Russian wolf-dog hybrids from wolves (Canis lupus) and dogs (Canis familiaris)?

Although wolves, dogs and their hybrids can be discerned by genetic analysis, the study of morphology-morphometry to discern the three groups remains important as genetic analysis is not always possible or too expensive. In this study we aim to differentiate the three subgroups by analyzing two morphometric and ten morphological characteristics in 329 canid skulls. After morphometric-morphologic allocation, we applied genetic analysis on 108 skulls based on 11 autosomal microsatellites to verify the morphometric-morphologic results. In 30 specimens genetic tests were unsuccessful. In addition, 23 samples from wolves (14 skins and 9 muscle samples) as well as 32 samples from modern dogs (8 hair and 24 blood samples) were used as reference data in the genetic analysis. Based on morphology-morphometry we diagnosed 322 wolves, four dogs and three hybrids. Genetic testing was done on 78 specimens: one presumed dog, three presumed hybrids and 74 of the wolves, as diagnosed morphologically before. All, but one, morphologically diagnosed wolves, were confirmed as being wolves genetically. That one was identified a hybrid genetically. From the four morphological dogs one was confirmed genetically, the other three had failed genetic tests. Of the three morphological hybrids one was genetically a dog. The results of this study indicate the absence of reliable morphological criteria for identifying skulls of hybrids, which is a consequence of the high morphological variability in dogs and wolves. However, the use of morphometric and morphological characteristics, helps to narrow the numbers of skulls that require genetic analysis for more precise identification.