Before and during the 1800s, North American plains bison barely survived a severe population bottleneck, declining from about 30 million bison spread across much of the continent to a few hundred animals saved from 5 or 6 local populations. While the remaining bison seemed to contain considerable genetic diversity, the amount of diversity lost with the bottleneck remained largely unknown.
However, a recent Park Service study, in cooperation with the University of North Dakota, suggests, not surprisingly, that abundant genetic diversity has been lost. The incomplete study has not been peer reviewed. Preliminary results are available on the Theodore Roosevelt National Park website. Non-nuclear mitochondrial DNA was analyzed from 67 extant bison and from bones of 73 bison recovered from archeological sites, representing pre- and post-bottleneck bison from across the country.
Researchers identified 43 different genetic groups of bison. Of these, only 10 were represented in today’s bison. The indicated loss of 76 percent of genetic diversity will compromise the ability of plains bison to adapt to changing environmental conditions, and to respond effectively to future disease challenges.
For the past 140 years, plains bison have been living in relatively small, genetically isolated herds. Small herds have continued to slowly lose genetic diversity through a process called genetic drift. Recently elevated awareness of this dilemma has prompted much official concern for the management, not just of bison, but of bison genetics. Maintaining the remaining genetic diversity of plains bison will require restoration of some large bison herds on large, diverse and wild landscapes.
Restoration of bison on the Charles M. Russell National Wildlife Refuge, a goal of our Coalition, will greatly improve the national management and preservation of plains bison genetics. This National Park Service study demonstrates the urgency of that restoration.
Thank you,
Jim Bailey, Montana Wild Bison Restoration Coalition
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