Population structure and history of North Atlantic Blue whales (Balaenoptera musculus musculus) inferred from whole genome sequence analysis

• Published in: Conservation genetics 2024-04, Vol.25 (2), p.357-371
• Main Authors: Jossey, Sushma, Haddrath, Oliver, Loureiro, Livia, Weir, Jason T., Lim, Burton K., Miller, Jacqueline, Scherer, Stephen W., Goksøyr, Anders, Lille-Langøy, Roger, Kovacs, Kit M., Lydersen, Christian, Routti, Heli, Engstrom, Mark D.
• Format: Article
• Language: English
• Subjects: Animal Genetics and Genomics; Aquatic mammals; Balaenoptera musculus; Biodiversity; Biomedical and Life Sciences; Cetacea; Conservation; Conservation Biology/Ecology; Ecology; Endangered species; Evolutionary Biology; Gene flow; Gene sequencing; Genetic analysis; Genetic diversity; Genetics; Genomes; Genomics; Life Sciences; Nucleotide sequence; Oceans; Plant Genetics and Genomics; Population; Population (statistical); Population genetics; Population structure; Research Article; Samples; Species diversity; Species extinction; Statistical analysis; Whales; Whales & whaling; Whaling; Whole genome sequencing; Wildlife conservation
• ISSN: 1566-0621; 1572-9737
• DOI: 10.1007/s10592-023-01584-5

Knowledge of genetic diversity and structure is essential for developing conservation strategies for endangered species. Blue whales were hunted to near extinction in the mid-twentieth century. Not-withstanding almost 380,000 animals killed globally, much remains unknown about their population structure and migration patterns. Herein, we use whole genome sequencing to elucidate the poorly understood population genetics of North Atlantic (NA) blue whales. We generated a de novo genome assembly for a NA blue whale to analyze 19 other whole genomic sequences and 31 complete mitochondrial genomes. Present-day and historical samples (earliest from 1876) from the Atlantic and Antarctic Oceans were included to understand the impact of whaling on the genetic diversity of this species. We found low but statistically significant population structuring and high genetic diversity. Demographic modeling using fastsimcoal2 rejected an absence of gene flow between eastern and western NA blue whales and suggested an asymmetric west to east gene flow. Introgression estimated using D-statistics between blue and fin whales ( Balaenoptera physalus ), was observed in all present-day samples. This gene flow was found to be unidirectional from fin whales to blue whales and accounts for ~ 3.5% of the NA blue whale’s genome. Our sequencing and population structure analyses provide a genomic baseline to inform ongoing conservation strategies for this iconic species.