P. Taberlet et al., LOCALIZATION OF A CONTACT ZONE BETWEEN 2 HIGHLY DIVERGENT MITOCHONDRIAL-DNA LINEAGES OF THE BROWN BEAR URSUS-ARCTOS IN SCANDINAVIA, Conservation biology, 9(5), 1995, pp. 1255-1261
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.