Studying Bison DNA

Bison cow and calf at Ordway Prairie Preserve
© Angela Benson/TNC

Tail hairs are providing insight into the genetic makeup of the Conservancy’s bison herds. A major obstacle to the conservation of bison is the discovery that most public and private herds previously evaluated contain evidence of past interbreeding with domestic cattle.

With the help of funding from the RJKOSE Foundation, the Conservancy's herds and other conservation bison herds will undergo studies to examine the degree of cattle interbreeding and genetic diversity within and among herds. The testing is being conducted by Texas A & M University. The results of this project will help guide herd management as well as long-term conservation of the bison genome.

From the 30+ million bison roaming the Great Plains when Louis and Clark traveled the Missouri River, by 1889, scarcely more than 800 free-roaming animals were documented. Current populations were primarily restored through the descendants of less than 200 animals used to establish five private herds owned by U.S and Canadian ranchers. Today, there are more than 500,000 in public and private herds. The Conservancy’s first bison herd was introduced on Ordway Prairie Preserve, in 1978. The Conservancy now has more than 4,300 bison on seven preserves in six states.

Tail hairs from 100 bison at Ordway Prairie were collected in the fall of 2006 and evaluated for cattle interbreeding in 2007. So far the results show only one animal has cattle genetics, but more testing is yet to be done (the average is 5 to 8 percent of a herd). The first set of results tested DNA inherited from the mother. In the next test, DNA from the fathers will be examined and results are expected in October 2007. During the fall round-up, Ordway Prairie Preserve staff will be collecting tail hairs from the remaining 180 bison to be evaluated this winter.

In North America, bison are recognized as an important species for maintaining grassland diversity, especially in land management systems that simulate the historical grazing-fire interaction and create a mosaic of habitat for other wildlife. This important ecological function has lead conservation organizations to primarily regard bison as an ecological management tool.

In order to ensure the long-term conservation of the bison species, coordinated efforts must be made to prevent the introduction of domestic cattle genetics and loss of genetic diversity. The results of these studies will help guide the Conservancy and other bison managers in deciding how to best maintain genetic diversity through management of herd size, sex/age structure, movement of animals between herds, and selective culling practices.

For more information on the status of other conservation herds, visit http://www.nrmsc.usgs.gov/projects/bison_5NP.htm