Anthropocene Magazine · Health

Ancient Bison DNA Reveals Insights for Herd Rehabilitation

New research published in Science utilizes ancient DNA to provide a roadmap for rehabilitating North American plains bison herds. The study analyzes genetic material from ancient bison dating back up to 20,000 years to understand the impact of historical events and inform future conservation strategies.

The study, led by Beth Shapiro, a researcher at the University of California Santa Cruz, reveals how the 19th-century collapse of bison populations affected their genomes and suggests a more genomically informed path forward for conservation. Historically, millions of bison roamed North America, but by the early 20th century, their numbers dwindled to a few hundred due to overhunting and habitat loss.

Conservation efforts have led to a partial recovery, with over 20,000 wild bison and more than 400,000 raised for commercial purposes. However, questions have persisted about genetic diversity, inbreeding, and potential genetic contamination from interbreeding with domestic cattle or the introduction of plains bison into wood bison territories.

By sequencing DNA from 115 ancient bison samples and 45 modern ones, researchers found that ancient plains bison exhibited remarkable genetic similarity across their range, suggesting free genetic flow. In contrast, modern wild plains bison are now confined to isolated pockets, forming at least four genetically distinct groups. The findings suggest managing these groups as a single herd, potentially using modern reproductive techniques to blend their DNA.

The study also offers hopeful news: collectively, modern herds retain genetic diversity comparable to their ancestors. Fears of widespread cattle DNA contamination appear overblown, with livestock DNA found in only about a third of modern bison genomes, and representing less than 2% of their genetic makeup.

For wood bison, the study indicates they remain genetically distinct from plains bison, having diverged about 3,000 years ago. Despite significant plains bison DNA (7% to 64%) in modern wood bison due to historical population transfers, they should continue to be managed separately. The research provides a crucial genetic baseline for 'healthy' bison diversity, enabling better management decisions for the species' future.

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