LOCALIZATION OF A CONTACT ZONE BETWEEN 2 HIGHLY DIVERGENT MITOCHONDRIAL-DNA LINEAGES OF THE BROWN BEAR URSUS-ARCTOS IN SCANDINAVIA

In Europe the brown bear (Ursus arctos) is represented by two differen t mitochondrial DNA (mtDNA) lineages, which probably diverged about 0. 85 million years ago. Scandinavia has been colonized by, representativ es of both lineages, from the north (eastern lineage) and from the sou th (western lineage), and now bears occur primarily in four main regio ns called female concentration areas. For management purposes the loca lization of the contact zone between these two genotypes is important. Using hairs as a source of DNA, 127 individual brown bears from throu ghout the Scandinavian Populations were assayed for lineage assignment . A part of the mtDNA control region was amplified via the polymerase chain reaction, and the product was either sequenced (14 individuals) or digested with two diagnostic restriction endonucleases (113 individ uals). Fifty-six and 71 bears were assigned to the western and eastern lineages respectively. The geographic distribution of the two genotyp es allowed precise localization of the contact zone. Only two males fr om each lineage had crossed the border between the two lineages. We us ed dispersal data from bears radio-marked as yearlings to determine wh ether potential mtDNA introgressions agreed with the dispersal behavio r of bears. The males in the ''wrong'' areas were all within the 95th- percentile dispersal distance from the ''correct'' area. Females were more philopatric than males, and none were found in the wrong areas. T he two female concentration areas flanking the contact zone were 134 k m apart. Thus, radiotelemetry results on dispersal distances could exp lain the occurrence of the males in the wrong genetic area. In the abs ence of information concerning possible male-mediated gene flow, a con servative management approach would be to consider the southern and th e three northern female concentration areas as two distinct conservati on units.