MORPHOMETRICAL CHARACTERISTICS OF THE COMMON SHREWS (SOREX-ARANEUS L)FROM INTERRACIAL HYBRID ZONES

Common shrews are subdivided into numerous chromosome races which make contact and form hybrid zones. To date, no strong differences in morp hology have been found between hybrid and pure race individuals from t he vicinity of such hybrid zones. To investigate this further, we carr ied out studies in Poland on three hybrid zones between races belongin g to the West and East European Karyotypic Groups using material colle cted from 1989 to 1994. Shrews were measured (head and body, tail and hindfoot length) and weighed. Statistically significant differences in morphology were only observed in the Stobnica/ Legucki Mlyn hybrid zo ne. The results indicated that both adult and immature animals belongi ng to the Stobnica race were smaller than those belonging to the Leguc ki Mlyn race. The hybrids were longer than individuals of pure race ka ryotype but the mean body mass of the hybrids was the lowest. At the p opulation level, the size of the shrews varied with value of a hybrid index. The absence of similar results for the Druzno/Legucki Mlyn and Drnholec/Bialowieza hybrid zones may reflect their narrowness compared with the Stobnica/Legucki Mlyn zone.