CHROMOSOME AND ALLOZYME VARIATION OF THE COMMON SHREW, SOREX-ARANEUS,IN DIFFERENT HABITATS

Chromosome and allozyme variation of the common shrew was studied in t hree different habitats (dry meadows, wet sedge bogs, and floodplain f orest) at Bialowieza, north-eastern Poland. Five karyomorphs of three polymorphic chromosome arm combinations, jl, gr, and mp, were found. T here were clear differences in the frequency of the twin-acrocentric m orphs between habitats. The frequency of the acrocentrics j and l was higher in dry meadows than in wet sedge bogs and in floodplain forest. In the case of two other polymorphic pairs, gr and mp, acrocentrics w ere found only in wet sedge bogs and in floodplain forest. Acrocentric s m and p occurred most often in floodplain forest. Of the 27 allozyme loci studied, 11 showed clear electrophoretic polymorphism. The mean number of alleles per locus and the percentage of polymorphic loci wer e higher in samples from floodplain forest than those in samples from dry meadows and wet sedge bees. Analysis of F-statistics indicated sig nificant differentiation for shrews among all samples from different h abitats. It can be supposed that chromosome and allozyme polymorphisms in the common shrew are related to environmental heterogeneity. It is also suggested that random factors may influence changes in frequenci es of acrocentric chromosomes and alleles in the population studied.