Genetic diversity and population structure among northern bottlenose whales,Hyperoodon ampullatus,in the western North Atlantic Ocean

Abstract

To assess population structure and genetic diversity among northern bottlenose whales (Hyperoodon ampullatus), we compared mitochondrial DNA control region sequences from three populations in the western North Atlantic Ocean. Skin-biopsy samples were collected from animals in the Gully off Nova Scotia, Canada, in 1996 and 1997 (n = 20), and teeth were obtained from whales taken in Davis Strait off northern Labrador (n = 20) and off northern Iceland (n = 5) between 1967 and 1971 by the historical Norwegian fishery. Only low levels of genetic diversity were found among the 45 animals sampled (three polymorphic sites over 434 base pairs defining four haplotypes; haplotype diversity (h) = 0.57, nucleotide diversity (π) = 0.0015). The cause of this low variability is unclear but may be due to a possible bottleneck event associated with the last glaciation. The distribution of mitochondrial DNA haplotypes between the Gully and Davis Strait populations was suggestive of regional differentiation (FST= 0.118, P = 0.024; ΦST= 0.145, P = 0.007). Animals taken off northern Iceland were not included in statistical analyses of population structure, owing to the small sample size. These data, in conjunction with other information collected to date, indicate that the Gully and Davis Strait populations should be considered separate stocks for management purposes.