Colonization history of north European field voles (Microtus agrestis) revealed by mitochondrial DNA


  • This work is part of Maarit Jaarola's PhD the& on the geographic structure of mtDNA and Y chromosome variation in field voles from northern Europe. The study constitutes part of a research project conducted by Hdkan Tegelstriim, designed to examine the effects of gladation and postgladation history on the population structure of north European animals using molecular techniques.

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The genetic structure of field vole (Microtus agrestis) populations from northern Europe was examined by restriction fragment length polymorphisms of mitochondrial DNA (mtDNA) in 150 individuals from 67 localities. A total of 83 haplotypes was observed, most of which were rare and highly localized geographically. Overall nucleotide diversity was high (134%), but showed a tendency to decrease with higher latitude. Two major mtDNA lineages differing by 2% in nucleotide sequence were identified. A southern mtDNA lineage was observed in field voles from Britain, Denmark and southern and central Sweden, whereas voles from Finland and northern Sweden belonged to a northern lineage. The strict phylogeographic pattern suggests that the present population generic structure in field voles reflects glacial history: the two groups are derived from different glacial refugia, and recolonized Fennoscandia from two directions. A 150–200-km-wide secondary contact zone between the two mtDNA groups was found in northern Sweden. Distinct phylogeographic substructuring was observed within both major mtDNA groups.