A hybrid zone between the chromosomal races Łęgucki Młyn and Popielno of the common shrew in north-eastern Poland: preliminary results

Abstract

A newly discovered hybrid zone between two karyotypic races, Łęgucki Młyn (g/r, h/k, i/o, j/l, m/n, p, q) and Popielno (g/r, h/q, i/k, j/l, m/n, o, p), of the common shrewSorex araneus Linnaeus, 1758 has been studied in north-eastern Poland. In the Łęgucki Młyn/Popielno hybrid zone the complex heterozygotes form theoretically only short meiotic chain configurations, consisting of four or five elements. In all hybrid populations a high frequency of complex heterozygotes was observed, varying from 0.30 to 0.43 between localities. In the centre of the hybrid zone the frequencies of telocentricsh andk increased. In two individuals of the hybrid populations (Krutyń I and Krutyń II), homozygous telocentric for chromosome armsh, i, k, o andq were observed.