A new paper in Genome Biology and Evolution, published by Oxford University Press, discovers that the endangered Mediterranean fin whale is not completely isolated from Atlantic groups. Both Atlantic and Mediterranean populations have declined for the past 200,000 years. Considering more recent threats to the whales, this finding has important implications for conservation, particularly considering increasing anthropogenic pressures.
Whales have long captured human fascination, due to their massive size but also because of their complex behaviors, migratory patterns, and ecological importance. Whales play a crucial role in maintaining ocean ecosystems by redistributing nutrients on which other marine life depends. Whales face increasing environmental pressures, from climate change to human-induced disturbances. As the climate crisis accelerates, genomic studies have become essential tools for investigating population structure, evolutionary history, and patterns of isolation in order to facilitate conservation efforts.
The fin whale (Balaenoptera physalus) is the second-largest whale species on earth, second only to the blue whale. Despite its classification as endangered, the fin whale from the Mediterranean Sea remains poorly characterized at the genomic level. Scientists previously identified the Mediterranean fin whale population as distinct from the North Atlantic populations through studies of sounds and whale tracking. Previous studies suggested the presence of both sedentary and migratory whale subgroups within the Mediterranean Sea. However, genetic characterization of this fin whale population has been limited, with only partial evidence for differentiation and possible gene flow. Researchers here attempted to reconstruct the Mediterranean fin whale's genetic structure, as well as its demographic and evolutionary history. The investigators inferred the potential for adaptation and vulnerability to increasing environmental disturbances by using the estimated level of genomic variability within the Mediterranean population.
By comparing genomes from the Mediterranean group with those of fin whales from the North Atlantic, North Pacific, and new sequences from Sea of Cortez, researchers evaluated the degree of genetic isolation and placed the Mediterranean population within a broader evolutionary and conservation context. The results show that although Mediterranean fin whales form a distinct genetic cluster, they are not fully isolated from North Atlantic populations. They also detected genetic differences within the Mediterranean group, with some individuals showing no evidence of admixture, whereas others display clear genetic contributions from other populations, likely reflecting ongoing migration and interbreeding.
"These incredibly fascinating mammals enrich the Mediterranean as an essential component of its ecosystem," said the paper's lead author, Roberto Biello. "By generating the first complete genomes for multiple individuals from this population, our study provides a valuable resource for investigating their adaptive potential in response to specific environmental pressures. Our findings highlight that effective conservation of this unique population will require both preventing population decline and maintaining connectivity with nearby populations."
The paper, "One Sea, Different Whales: Genomics Sheds Light on a Small Population of Fin Whales," is available (at midnight on April 28th) at https://academic.oup.com/gbe/article-lookup/doi/10.1093/gbe/evag084 .
Direct correspondence to:
Roberto Biello
Department of Life Science and Biotechnology
University of Ferrara
44121, Ferrara, ITALY
