The location of the Mus musculus/M-domesticus hybrid zone in the Balkans:: clues from morphology

Three morphological characters were used to depict the position of the hybrid zone between two species of house mice, M. musculus Linnaeus, 1758 and M. domesticus Schwarz et Schwarz, 1943, across a vast area covering countries of the former Yugoslavia, Albania, Bulgaria and Greece. Quantitative approach based on a morphological index (MI), resembling the hybrid index widely used in allozyme-based genetic studies, was used. The zone crosses Slovenia south of the Sava River, and then follows the Dinaric Mts to Montenegro and northern Albania. Contrary to many previously published results, the zone was found to run parallel with northern borders of Albania and the former Yugoslavian Macedonia, about 150 km north of the Greek border, thus giving its course rather "shallow" appearance at this part of the Balkan Peninsula.