Researchers have sequenced 160 bison genomes, assembling a genetic record of the species stretching back 20,000 years, according to CBC. The study, published in the journal Science, was led by paleogeneticist Jonas Oppenheimer and the Paleogenomics Lab at the University of California, Santa Cruz, with contributions from nearly 40 scientists, many of them Canadian. Its findings suggest that the near-extinction of bison in the late 19th century left the species with an unexpected genetic legacy — one that could shape how remaining herds are managed.
Why it matters
Before hunting and government campaigns reduced them to a fraction of their former numbers, bison moved freely across North America in vast herds. Today they live in isolated, carefully managed groups. According to CBC, the new research indicates that this fragmentation, rather than a wholesale loss of genetic diversity, is now the central challenge facing the species. Oppenheimer told CBC that understanding the animal's genetic history could help researchers support herds into the future.
A continent-wide genetic map
The project drew on DNA from ancient bison bones and from living animals. Researchers sequenced 115 ancient genomes and 45 modern ones, then combined that data with 52 genomes sequenced previously, producing what CBC describes as the largest genetic map of the species to date.
Modern samples came from managed herds in Canada and the United States, including animals in Elk Island National Park and Wood Buffalo National Park in Alberta, as well as free-ranging herds in the province's north at Ronald Lake and Wabasca. Ancient DNA was gathered from specimens held in collections across the United States, Canada and Russia, among them material from Parks Canada and the Royal Alberta Museum in Edmonton.
Chris Jass, curator of quaternary paleontology at the Royal Alberta Museum, told CBC it is rewarding to see ancient fossils inform modern herd management. He called the study a strong example of collaboration, adding that it illustrates why institutions keep such collections for long periods — so that new techniques can be applied to evolutionary and biological questions as they arise.
A bottleneck with a surprising outcome
According to CBC, bison across most of North America were genetically similar for thousands of years before colonization, interbreeding freely and maintaining a largely uniform gene pool. That changed in the late 19th century, when intensive hunting and government campaigns removed millions of animals from the plains.
Oppenheimer told CBC that genetic diversity did not initially suffer from the collapse, because populations had been so widespread and uniform beforehand. The research found that a surprising amount of diversity survived, but it is now confined to separate herds that no longer mix. Much of the modern genetic differentiation persisted by chance, carried within the DNA of each individual herd.
"We had assumed that there would be a huge loss," Oppenheimer told CBC. "As a whole, it doesn't seem like all that much genetic diversity is lost. But each particular herd has its own kind of distinct, genetic signature now because of that very recent history."
He described the current pattern as the legacy of the bottleneck the species experienced when humans drove it close to extinction.
Cattle ancestry and a subspecies split
The study also examined a question that has long surrounded bison genetics. According to CBC, the researchers determined that, contrary to common belief, many bison carry no cattle ancestry at all. Where such ancestry does appear, it typically accounts for less than one per cent of an animal's genome.
The work also documented the division between the two recognized types of bison. Wood bison are larger and heavier, with a humped profile, and are suited to northern boreal forests and aspen parklands. Plains bison are smaller and historically ranged across the open grasslands and prairies of the Great Plains.
CBC reports that the two diverged roughly 3,000 years ago, as shifts in climate allowed boreal forests to expand. Human intervention later brought them back into contact, most notably when plains bison were relocated into Wood Buffalo National Park in the 1920s.
The findings add detail to a picture conservationists have been building for years: a species whose genetic story is not one of simple erasure, but of diversity redistributed into scattered, isolated pockets. What happens next will depend on how that knowledge is applied to the management of the herds that remain.
