Ancient DNA Reveals Arctic Whale Mysteries

by AMNH on

Research posts

A team of researchers has published the first range-wide genetic analysis of the bowhead whale—a baleen whale that lives in Arctic and sub-Arctic waters—using hundreds of samples from both modern populations and archaeological sites used by indigenous hunters thousands of years ago.

A wide aerial photograph of a bowhead whale swimming between large ice floes. The top of its head and its blowhole are above the water surface.
A bowhead whale amid the ice floes off Point Barrow, Alaska.
Brenda K. Rone, NOAA/AFSC/NMML

The study, conducted by scientists from the Wildlife Conservation Society, the American Museum of Natural History, City University of New York, and other organizations, attempts to shed light on the impacts of sea ice and commercial whaling on this threatened but now recovering species. The study appears in the most recent edition of the journal Ecology and Evolution.

The authors examined mitochondrial DNA from whales from all four or five putative populations—the Canada-Greenland population (sometimes designated as two separate populations, the Baffin Bay-Davis Strait and Hudson Bay-Foxe Basin populations), Bering-Beaufort-Chuckchi Seas, the Okhotsk, and the Spitsbergen populations—for the purpose of gauging gene flow between those groups.

In addition to using DNA samples collected from whales over the past 20 years, the researchers collected genetic samples from ancient specimens—extracted from old vessels, toys, and housing material made from baleen—preserved in pre-European settlements in the Canadian Arctic.

The ancient samples were brought to the Museum’s Sackler Institute for Comparative Genomics, where researchers isolated and amplified segments of mitochondrial DNA, which is passed on exclusively through the maternal lines of a population.

The genetic analysis revealed differences found between ancient and modern population diversity, including the recent disappearance of unique maternal lineages over the past 500 years, the possible result of habitat loss during the Little Ice Age (a period of climatic cooling that occurred between perhaps the early 1500s to mid-1800s) and/or extensive whaling in the region.

Another finding of the study: the frozen—and seemingly impassable—inlets and straits separating Atlantic and Pacific populations appear to be little obstacle to the ice-savvy and morphologically adapted bowheads. Over time, this analysis revealed the two populations to be closely related, meaning that at some point they must have forded the icy inlets to meet and, sometimes, mate. The routes they traveled remain unclear. 

The authors point out that understanding the effects of shifting sea ice conditions and commercial whaling are important for future management decisions for bowhead whales, particularly in light of the disappearance of sea ice due to climate change, maritime tourism, and increased shipping in the Arctic environment.