Patterns of genetic diversity in a black bear population indicate recent immigration

To determine whether the recent history of a black bear (Ursus americamis) population includes significant immigration, we examined patterns of genetic diversity in mitochondrial DNA (mtDNA) sequences from 37 individuals from the upper North Fork of the Flathead River (NFFH), Montana. Two major evolutionary clades of lineages were identified which differed at an average of 4.4% of nucleotide positions. The divergence found between these clades was much larger than expected and was consistent with the hypothesis that genetic diversity in this population has been supplemented by immigrants from other populations.