TWS 2015 Student Poster Winner: Yellowstone Bison Genetics

By Joshua Rapp Learn

American bison. Image Credit: David Forgacs

A genetic mutation once thought to be linked to an inherited mitochondrial disease among American bison causes no detectable problems to the giant herbivores, according to ongoing research.

“These genetic mutations do not appear to be associated with any disease in bison,” said David Forgacs, a PhD student at Texas A&M University and the second place winner in the PhD category of the student poster contest at the 2015 Conference of The Wildlife Society.

American bison in Yellowstone National Park Image Credit: David Forgacs
American bison in Yellowstone National Park Image Credit: David Forgacs

He and others looked at the DNA of bison to find the resident animals had no genetic overlap with cattle. Instead, they contained genes from two major ancestral strains — those descended from the last 22 endemic animals that remained in Yellowstone National Park in 1902 and those descended from 18 captive animals introduced at that time.

The genetic mutation came entirely from those 18 introduced animals, he said, but the percentage of animals with that mutation hasn’t dropped over the years. This finding indicates that there is no significant negative selection associated with this mutation.

In spite of the small number of animals that the current bison trace back to, Forgacs said the Yellowstone herd displays a high level of genetic diversity.

David Forgacs stands in front of his winning poster at the TWS 2015 Conference in Winnipeg. Image Credit: Caitlin Curry
David Forgacs stands in front of his winning poster at the TWS 2015 Conference in Winnipeg. Image Credit: Caitlin Curry

“[Genetic diversity] is definitely on the rebound since those major population bottlenecks,” he said, adding that this diversity seemed to be spread evenly among the population, without any discernable population subdivisions based on mitochondrial DNA.

Forgacs said that these findings are important because they could help the National Park Service with population management meant to appease ranchers nervous about the spread of brucellosis in nearby land surrounding Yellowstone.

“Assessing the genetic health of the population helps the NPS create the best way of managing the population without affecting the overall genetic diversity,” he said.

Joshua LearnJoshua Rapp Learn is a science writer at The Wildlife Society. Contact him at jlearn@wildlife.org with any questions or comments about his article.

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