PHYLOGENETIC STRUCTURES OF THE HOLARCTIC SOREX-ARANEUS GROUP AND ITS RELATIONSHIPS WITH S-SAMNITICUS, AS INFERRED FROM MTDNA SEQUENCES

The shrews of the Sorer araneus group, characterized by the sexual chr omosome complex XY1Y2, have been intensively studied by morphological, karyotypical, and biochemical analyses. Nevertheless, the phylogeneti c relationships among the species belonging to the araneus complex are still under debate, as different approaches gave often contradictory results. In this paper, partial nucleotide sequences of the mitochondr ial DNA cytochrome b gene (1011 bp) were determined for 6 species of t he araneus group from Eurasia and North America. We also included in t he data set the sequences of Sorex samniticus, whose relationships wit h the araneus group remain controversial. Three other species represen ting two major karyological groups were also examined. Both parsimony and distance trees strongly support the monophyly of the araneus group . Sorex samniticus is significantly more closely related to the araneu s complex than to the other species included in the analysis. Based on the branching pattern within the araneus group, an attempt has been m ade to reconstruct the colonization history of the Holarctic region.