Ancient Bottlenose Dolphin Genome Gives Insight Into Coastal Adaptations

Common bottlenose dolphins (Tursiops truncatus) rapidly adapted to new coastal environments when they emerged thousands of years ago, a new study in Nature Communications reports. An international team of researchers analyzed the genomes of four ancient dolphins that lived in the eastern North Atlantic Ocean between about 5,600 years and 8,600 years ago when new coastal habitats arose in the region. After determining that one sample, dubbed SP1060, was representative of the ancient dolphins, the researchers focused their attention on it to find that adaptation to the new coastal environments occurred quickly and arose from standing genetic variation. The researchers also examined the relationship between the ancient dolphin and modern coastal and pelagic dolphins to not only find that modern coastal dolphins, but also the offshore-dwelling ones maintain these variants. "We show that parallel adaptation occurred rapidly after the emergence of new coastal habitats," the researchers write in their paper. "We also provide insights into how past admixture retained coastal-adapted ancestry at low frequency in pelagic populations, which selection can then act upon to promote rapid adaptation."