Maintenance of high levels of allelic variation in spite of a severe bottleneck in population size: the brown bear (Ursus arctos) in the Western Carpathians

Genetic variation in an isolated brown bear population of the Western Carpathians was studied by electrophoretic analysis of 51 presumptive allozyme loci. In spite of a severe population bottleneck at the beginning of the 1930s (40 survivors), average heterozygosity (H=5.3%) was within the range commonly found in mammals and the mean number of alleles per polymorphic locus (A_p=3, over five polymorphic loci) was very high. Possible reasons for the maintenance of high allelic variation are discussed.