Cattle ranchers saved American bison (known as buffalo) from extinction by capturing them and establishing bison herds in the 1870s and 1880s. The U.S. Army and Native Americans helped. The Army protected the last bison in Yellowstone National Park from poachers, and a Native American named Samuel Walking Coyote captured some bison calves in Montana and sold them to the Pablo-Allard ranch, which established a large bison herd in the Flathead Valley of Montana.
Ranchers, soldiers and Native Americans should get credit for this conservation success and should be appreciated by today’s environmentalists.
The primary established bison herds that supplied stock to start new herds or augment existing herds were the Goodnight herd in Texas; the Jones herd in Kansas; the Dupree herd in South Dakota; the McKay and Alloway herd in Manitoba, Canada; and the Walking Coyote/Pablo-Allard herd in Montana.
All of these ranches, except the Walking Coyote/Pablo-Allard herd, deliberately experimented with cattle and bison interbreeding. Incidental interbreeding of cattle and bison that were run together on these ranches also occurred. There are also records of cattle-bison hybridization in the eastern U.S in the mid-1700s and early 1800s, but their fate is unknown.
What is the effect of this cattle-bison hybridization on living bison herds? Research suggests that most bison herds maintained small amounts of cattle genes following this interbreeding. Exceptions included the herds in the Yellowstone, Wind Cave and Elk Island national parks, which were thought to be without cattle genes. However, a recent study by researchers at Texas A&M University, led by James Derr, Ph.D., and Brian Davis, Ph.D., shows that all living bison herds in the U.S. and Canada, including these three herds, have some cattle genes in their DNA. The study was published in the scientific journal Nature and is titled “Genomic evaluation of hybridization in historic and modern North American Bison.”
This study analyzed the DNA of the entire genomes of 25 bison and 1,842 cattle from the herds and breeds shown in Table 1. Whole genome sequencing provided better resolution than previous research that used limited numbers of genes.
Using complex laboratory and data analyses, the A&M scientists identified millions of genes (called single nucleotide polymorphisms) characteristic of either bison or cattle. Among the herds, less than 3 percent (0.24-2.45 percent) of the bison’s DNA was from cattle, consistent with the past interbreeding between the species.
You can think of it like a DNA profile for a bull, in which the DNA indicates different genes affecting a trait—for example, birth weight. In this case, the DNA indicates a gene’s origin in either cattle or bison, and some DNA that is characteristic of cattle was found in bison.
Does it matter? From a practical standpoint, not really. After four or five generations of backcrossing to bison, the hybrids’ descendants are indistinguishable from pure bison. It’s possible that the bison and cattle crossbreeding increased genetic variation and added genes that might increase fitness (e.g., disease resistance).
There also could be negative effects of cattle genes in bison, but selection in free-ranging herds—such as Yellowstone with its cold winters, limited forage, grizzly bears and wolves—would probably eliminate many detrimental genes.
However, there is some potential relevance for conservation efforts. The bison in Yellowstone are still being considered for an Endangered Species Act (ESA) listing after a court ruling in January. There were previous ESA petitions to list the Yellowstone bison in 2007, 2014, 2015 and 2018. Some of these petitions claimed Yellowstone bison were genetically pure, without cattle genes from past interbreeding, even though Yellowstone received bison with some cattle in their ancestry from the Pablo-Allard and Goodnight herds. The A&M study should invalidate that claim.
There are now about a half million bison in private ranches and wild herds in the U.S. and Canada (see WLJ, April 22 and Oct. 7, 2019). Private bison are marketed for meat, hides and hunting, and wild herds are important to conservationists. The Texas A&M study provides good science, which will contribute to sound management of bison.
Much of the information on bison in this article is described in the Texas A&M paper and the article “New Texas A&M Research Documents Domestic Cattle Genetics in Modern Bison Herds” found in the Texas A&M Today at tamu.edu. — Dr. Matthew Cronin
(Matthew Cronin was a research professor at the University of Alaska and is now a scientist with Northwest Biology Company LLC in Bozeman, MT. He can be reached at croninm@aol.com. A full list of references can be found at wlj.net.)
Matthew Cronin is a scientist with Northwest Biology Company LLC in Bozeman, MT, and was a research professor at the University of Alaska.
