Chromosome and allozyme variation of the common shrew, Sorex araneus, in different habitats

Abstract

Chromosome and allozyme variation of the common shrew was studied in three different habitats (dry meadows, wet sedge bogs, and floodplain forest) at Bialowieza, north-eastern Poland. Five karyomorphs of three polymorphic chromosome arm combinations, jl, gr, and mp, were found. There were clear differences in the frequency of the twin-acrocentric morphs 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 were found only in wet sedge bogs and in floodplain forest. Acrocentrics 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 were higher in samples from floodplain forest than those in samples from dry meadows and wet sedge bogs. Analysis of F-statistics indicated significant differentiation for shrews among all samples from different habitats. 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 frequencies of acrocentric chromosomes and alleles in the population studied.