Whole Mitochondrial Genome Analysis of Killer Whales Reveals the Presence of Resident and Transient Ecotypes Around Hokkaido
ABSTRACT In the North Pacific, there are at least three genetically different ecotypes of killer whales ( Orcinus orca ), referred to as resident, offshore, and transient. A previous study suggested that killer whales around Hokkaido belong to fish‐eating (resident and/or offshore ecotypes) and mammal‐eating (transient ecotype) groups. These results were supported by haplotypes based on the combination of 1193 bp of cytochrome b and 420 bp of the control region in mitochondrial genomes. However, this analysis was not sufficient to discriminate between resident and offshore ecotypes because of the short sequence lengths. In this study, we analyzed whole mitochondrial genomes of 25 killer whales sampled around Hokkaido to clarify the ecotypes and mitochondrial genome haplotypes. Phylogenetic analysis revealed the presence of resident and transient ecotypes around Hokkaido. The whales identified as residents shared an identical haplotype, which is the most common haplotype in the western North Pacific. In contrast, the transients around Hokkaido exhibited eight haplotypes, including seven novel ones among the 19 individuals, and their haplotype richness was the highest among the North Pacific populations. This result suggests that the Hokkaido coast served as a refugium for transient killer whales during the Last Glacial Maximum.
Authors
- Tadasu K. Yamada (ORCID: https://orcid.org/0000-0002-7396-1588)
- Yu Sato (ORCID: https://orcid.org/0000-0002-3596-8439)
- Shin Nishida (ORCID: https://orcid.org/0009-0006-5719-6771)
- Yoko Mitani (ORCID: https://orcid.org/0000-0002-7420-0596)
- Yoshikazu Uni
- Hiroshi Ohizumi
- Manabu Kawai (ORCID: https://orcid.org/0000-0003-3506-9895)
- Takashi Hayakawa (ORCID: https://orcid.org/0000-0002-1037-0350)
- Masao Amano (ORCID: https://orcid.org/0000-0001-9495-5315)
- Shimpei F. Hiruta (ORCID: https://orcid.org/0000-0001-7890-1720)
- Takashi Matsuishi (ORCID: https://orcid.org/0000-0003-0884-3523)
- Miho Inoue‐Murayama (ORCID: https://orcid.org/0000-0003-4249-876X)
- Akira Shiozaki (ORCID: https://orcid.org/0000-0001-6705-6955)
- Motoi Yoshioka (ORCID: https://orcid.org/0000-0003-4707-3760)
- Shigeo Saino
- Fumio Nakahara (ORCID: https://orcid.org/0000-0002-0224-9446)
- Y. Kita (ORCID: https://orcid.org/0009-0004-6638-5342)
- Yuko Tajima (ORCID: https://orcid.org/0009-0001-7119-2455)
- Akhtar M.T. (ORCID: https://orcid.org/0000-0002-1271-8592)
- Momoka Suzuki (ORCID: https://orcid.org/0009-0002-6311-8981)
Institutions
- University of Miyazaki (JP)
- Tokyo University of Agriculture (JP)
- Tokai University (JP)
- Mie University (JP)
- Hokkaido University (JP)
- Kyoto University (JP)
- Tokiwa University (JP)
- Hakodate University (JP)
- May Institute (US)
- Mount Fuji Research Institute (JP)
- Japan Wildlife Research Center (JP)
- National Museum of Nature and Science (JP)
- Nagasaki University (JP)
Publication Details
- Journal
- Marine Mammal Science
- Published
- 2025-12-17
- DOI
- https://doi.org/10.1111/mms.70107
- Primary Topic
- Marine animal studies overview
- Type
- article
- Field-Weighted Citation Impact
- 0.00