WYOMING — Wyoming State Archaeologist Spencer Pelton at the University of Wyoming (UW) was involved with a new study on the history of North American bison, which has been published in the journal Science.
Researchers from over 30 institutions and organizations sequenced 115 ancient and 45 modern bison genomes from across the continent to show how the iconic mammal has evolved over the past 20,000 years. The research includes the yearslong slaughter of bison herds across the West in the 1800s, which nearly led to their extinction. Bison bones collected at Wyoming archaeological sites, and housed at UW, offered genetic material for the study.
According to a summary of the study on UW’s website, two major findings emerged from the investigation. Notably, researchers found that before the human-driven population collapse, bison ranged widely across the continent and were genetically connected. Genetic diversity remained prominent until populations became isolated in attempts to conserve the species. Additionally, scientists found limited cattle ancestry in modern bison herds, despite previous assertions that almost all bison have some cattle ancestry from breeding experiments. Researchers say that the amount of cattle genes is small enough that it could eventually be eliminated from those herds.
“This study provides, perhaps, the most comprehensive assessment of North American bison and how they’ve changed over the past 20,000 years, and it’s noteworthy that so much of the genetic material used in the study comes directly out of UW’s archaeological repository,” Pelton said. “This really demonstrates the value of the university’s investment in collections management.”
Toward the end of the 19th century, the total population of North American bison plummeted from tens of millions to just a few hundred. Efforts by individuals, Tribes, government entities and others helped to bring the animals back from the brink of extinction, and wild populations are now estimated at 30,000 (privately managed herds are made up of about 500,000 animals). Modern bison are typically managed in small, isolated herds, according to UW, along with some larger, wild herds in Grand Teton National Park and Yellowstone National Park. Canada’s Wood Buffalo National Park also retains a wild herd of wood bison.
The team of researchers found cattle ancestry in just 32% of the 97 modern plains bison samples that were analyzed.
“Together, these results suggest that cattle ancestry is much less common than previously thought and could potentially be lost over time through [genetic] drift, as long as gene flow between herds is frequent enough to prevent particular segments of cattle ancestry from becoming fixed within herds,” the scientists wrote.
The new findings are mostly encouraging, the researchers said, because the anticipated consequences of the near extinction — widespread loss of genetic diversity and pervasive cattle genetics — appear to be less pronounced than previously believed. The teams believes that the future of bison in North America depends on management strategies that pull from the newly discovered historical information.
