Phylogenetic analysis of killer whale (Orcinus orca) and humpback whale (Megaptera novaeangliae) populations along the Northern Norwegian fjords and adjacent waters

Abstract

Killer whales (Orcinus orca) and humpback whales (Megaptera novaeangliae) are two widely distributed cetacean species and both seasonally congregate in the waters off the fjords in Northern Norway to feast on the Norwegian Spring Spawning herring (Clupea harengus). With phylogenetic analysis of complete mitochondrial genomes, obtained by shotgun sequencing, from individuals sampled through four years, this study has attempted to shed light on the geographical origin and phylogenetic position of Norwegian killer whales and humpback whales in the global context of each species. In total, 19 haplotypes were identified among 134 killer whales, and 18 haplotypes were identified among 94 humpback whales. The killer whales sampled in Northern Norway showed structuring between individuals and cluster in a clade with other individuals from Eastern North Atlantic Ocean previously described in literature. The humpback whales showed less clear clustering within the global context but have revealed a potential connection of four individuals with haplotypes from the Southern Hemisphere. Overall, this study suggests that the feeding aggregations in Northern Norway gather killer whales mainly from Eastern North Atlantic Ocean, and humpback whales from the North Atlantic and possibly from the South Atlantic Ocean.