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Go DeeperTallgrass Prairie Preserve Bison Return to Iowa Bison, Fire and the Tallgrass Prairie Preserve
Round-Up Video |
Cowboy Forensics
“The results are in,” says James Derr, looking up from his laboratory bench, where a set of DNA samples from Tallgrass bison has been run through a molecular-testing device called a “gel.” The results — bands of blue and black creeping across a white canvas — don’t look like much. But to Derr, they read like the morning newspaper.
With his turquoise-studded belt buckle, black leather boots and easy Western drawl, Derr looks as though he belongs in a saloon, not in a sterile genetics lab. But this forensics cowboy is a professor of veterinary pathobiology at Texas A&M University.
He takes a swig of coffee and turns on the black light above the laboratory bench to take a closer look at the latest results. “This one,” he says, pointing to two blue bands running in close parallel, “is a sure-enough cow.”
Derr’s colleague, Natalie Halbert, another pathobiology professor at A&M, looks at the fingers of color and nods in agreement. Over the past 10 years, this duo has analyzed DNA in hair and blood samples from more than 100 herds around the country, trying to distinguish and separate out the bison from the beefalo.
What they’ve found is disconcerting. Many herds have yet to have their DNA checked out entirely, but so far only 10,000 of the half-million bison in North America have turned up free of cattle genes. Almost 90 percent of the private herds include animals that have tested positive. Public herds, such as those at Yellowstone, show more promise, as only 6 percent have turned up positive for cattle genes.
Herds owned for conservation purposes, such as at Tallgrass, remain largely untested — until now, that is. With funding from the Conservancy’s Rodney Johnson-Katherine Ordway Stewardship Endowment, Derr’s lab is examining hair and blood samples from 12 conservation herds — 6,000 animals in all — including those run by the Conservancy, Kansas State University, the American Prairie Foundation and Parks Canada.
So far, there’s no scientific evidence documenting how cattle genes affect bison, but Derr and Halbert suspect it isn’t good. “It’s assumed that bison with cattle mitochondrial DNA are less energy-efficient than their pure counterparts,” says Derr, who notes that cattle have shorter lives and produce more offspring than longer-lived, less productive bison.
“Bison with cattle genes may also exhibit physiological characteristics of cattle that make them less desirable grazers for grasslands,” says Derr. “But we’re not 100 percent sure yet.”
While Derr and Halbert are worried about the future of prairie restoration, their big concern is preventing the “genomic extinction” of the bison. They don’t want to see the restoration of this native species lost to an unintentional watering down of the gene pool.
“We don’t want to call anyone’s kid ugly,” says Derr, who is quick to point out that it will be up to individual herd managers to decide what to do with the results from his tests.
“But it’s an absolute crime to take hybrids into a herd with no evidence of cattle genes.”
Whatever the future of bison, determining which herds possess cattle genes is the first step toward protecting the species genome and propagating herds that are cattle free.
The second step will be building out larger populations of pure bison. Right now, only five conservation herds in North America number more than 1,000 animals. “We need that many individuals in each herd in order to achieve what scientists have termed ‘sustainable,’” says Derr. He says that larger populations — and larger gene pools — are better equipped to avoid the negative effects of inbreeding, such as the loss of genetic diversity.
The Conservancy could have an important role to play in the genetic conservation of the species. With more than 5,000 bison on nine preserves in seven states, the Conservancy has the kind of acreage — and potentially the kind of bison — to establish satellite herds of eligible breeders.
“The decisions herd managers make today are going to determine what genes are preserved — what animal is preserved,” says Derr.
Buffalo Magic
Loud, guttural bellows and the reverberation of one-ton animals clashing against one another and the rails of the steel holding pen drown out the songs of meadowlark and killdeer on the prairie at Tallgrass. A wrangler patrols the corral on a catwalk high above the ruckus. He yells out with a twang, “Get off the gate! Get off the gate! Get off the gate!”
It is well before 9 a.m., and the corral is already cranking. The wranglers use rattle paddles and electric prods to sweep bison through a series of narrowing alleyways toward the squeeze chute that will hold each bison in place for its 50-second medical exam.
“This project is about filling in the final piece of a large puzzle,” says Hamilton, as a massive bison leaps into the squeeze chute and is promptly embraced and immobilized by its iron bars. A cowboy administers an inoculation and calls out the animal’s weight and sex (“912! Bull!”), while Hamilton pulls a few hairs from the animal’s tail using a pair of pliers. He holds the bundle of hairs up to the light to see if the follicles came, too.
“The root material is where the DNA is,” says Hamilton. “That’s the buffalo magic.” He grabs a coin envelope and stuffs the coarse black hairs inside.
After Hamilton completes the “yank job,” the squeeze chute opens and the bull bucks and gallops out of the corral toward the open prairie and the rest of the herd. He doesn’t stop until there’s a good football field or two between himself and his handlers.
Nature picture credits: Photos © Ann E. Cutting
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