Comparative morphometric study of the Slovakian wildcat population (Felis silvestris silvestris): Evidence for a low rate of introgression?

Statistical analyses of 60 cranial and six postcranial characters of 105 domestic cats and 77 wildcats from Slovakia showed that the two forms can be separated on the basis of just a few morphometric traits. To test the distinguishing power of these characters we first pre-classified the specimens of our sample as wildcat or domestic cat on the basis of the cranial volume, which is a non-overlapping diagnostic character in most populations investigated so far. Pearson's r correlation matrix of all 60 cranial traits showed a high degree of correlation. A linear discriminant analysis, excluding cranial volume, showed that maximal length of M₁, distance between foramen rotundum and foramen ovale and diameter of porus acusticus externus was necessary to separate the two forms. When postcranial traits were included, tibia length, femur length and distance between foramen rotundum and foramen ovale sufficed to assign the individuals to the correct group, with just one misclassification. Distinguishing between all four possible groups (domestic/wild versus male/female) was only partially possible, with a minimum 5% misclassification rate always with regard to sex. The results of the principal component analysis underlined that domestic cats and wildcats can be identified unequivocally on the basis of a set of morphometric measurements even in the absence of the best discriminating traits. In comparison with a reference population from Thuringia, Germany that the authors had studied previously, the morphological differences between domestic cats and wildcats are much more pronounced in Slovakia. Moreover, the ranking of the diagnostic value of characters differs between populations. As possible explanations for this finding, we discuss the theory of an east-west gradient in body size caused by a more maritime climate in the west and a more continental one in the east, and that of a lower degree of introgression and hybridization between the two forms in the Slovakian population.