STUDY OF GENE FLOW-THROUGH A HYBRID ZONE IN THE COMMON SHREW (SOREX-ARANEUS) USING MICROSATELLITES

The common shrew (Sorer araneus) is subdivided into several chromosoma l races. As hybrid zones between them have been characterized, this or ganism is of particular interest in studying the role of chromosomes i n speciation. Six microsatellite loci were used to evaluate the level of gene how in the S. araneus hybrid zone between the Cordon and Valai s races. Most of these loci were very polymorphic, the total number of alleles detected per locus ranging from 3 to 20. Using Mantel tests, we showed that the effect of rivers as barriers to gene flow is less i mportant at this sampling scale. The effect of the chromosomal race is of particular importantance in diminishing gene flow.