GENETICALLY DISTINCT BLACK BEAR POPULATION FOUND IN ARKANSAS

GENETICALLY DISTINCT BLACK BEAR POPULATION FOUND IN ARKANSAS

This map shows the current range of black bears in Arkansas and Louisiana. The researchers have found that the Ozark, Ouachita and inland Louisiana bears genetically resemble the bears imported from Minnesota in the 1950s and 1960s, while the White River Refuge bears and the coastal Louisiana bears remain genetically distant from the others.

Researchers take blood samples from anesthetized bears. University of Arkansas researchers used DNA from 82 different bears to conduct their study.

The black bear once dominated the North American landscape, but over-hunting in the 1800s and 1900s caused its population to crash. Today sub-species of black bears exist in small pockets across the country, and some of those populations, like the Louisiana black bear, remain threatened. Black bears had disappeared from most of Arkansas in the 1940s, and Minnesota black bears were introduced to the Ozarks, Ouachitas and inland Louisiana in the 1950s and '60s.

Undergraduate student Ildiki Csiki loads a gel used to compare microsatellite DNA markers in the black bear populations of Louisiana and Arkansas

Microsatellite gels like this one were prepared and compared to determine the genetic relatedness of black bears in Louisiana, Arkansas and Minnesota.

This shows the relatedness of the black bear subspecies in Arkansas, Louisiana and Minnesota.

FAYETTEVILLE, Ark. - University of Arkansas biologists used microsatellite DNA markers to examine the genetics of black bears in Louisiana and Arkansas and found that the black bear population in Arkansas’ White River National Wildlife Refuge shows the greatest genetic distance from other black bear populations in Arkansas and Louisiana. These include a threatened sub-species in Louisiana and other bear populations in Arkansas that resulted from imported black bears from Minnesota in the 1960s. This finding may lead to changes in how state and federal governments manage the black bears in both states—especially the White River black bears—and may even lead to changes in the animal’s status under the Endangered Species Act.

University of Arkansas biologists Kimberly Smith and Douglas Rhoads, biologists Joseph D. Clark and Richard Pace and undergraduate students Ildiki Csiki, Cynthia Lam, Audie Key and Erica Coulter report their findings in an upcoming issue of the Journal of Mammalogy.

"Our study suggests that the White River Refuge population is the most genetically distinct," Rhoads said. "More attention should be paid to the White River population."

Their findings contradict a previous study that appeared in the Journal of Heredity claiming a close relationship between the White River Refuge population and the coastal and inland Louisiana populations. However, Rhoads points out that the first study used lower resolution gels and less precise equipment that probably did not allow for the detection of one or two base pair differences.

The outcome of this genetic lineage debate could mean different fates for the bears. The White River Refuge population has bloomed to about 600 bears, and as their numbers have increased, so have their interactions with humans. The Arkansas Game and Fish Commission started a limited hunting season on these bears in 2001 and 70 animals were harvested. If the 600 White River Refuge black bears become lumped in a family with the Louisiana black bear, the increase in population could bump the mammal off the threatened list. On the other hand, if the inland Louisiana bears prove to be hybrids of the Minnesota sub-species, then they should not continue to be protected under the Endangered Species Act—which leaves both the bears and their habitat vulnerable to exploitation.

At one time, the black bear had no such worries. Black bears once enjoyed one of the widest ranges of any large mammal in North America, ranging from eastern Canada to Guatemala. However, hunters decimated their populations in the 19^th and 20^th centuries, leaving behind small pockets of bears in some places and eliminating them from the landscape in others.

By the 1940s, only an estimated 25 to 50 bears remained in Arkansas, mostly in what later became the White River National Wildlife Refuge. In the 1950s and 1960s, efforts were made to re-populate both Arkansas and Louisiana bear populations with bears from Minnesota, with about 254 bears released in the Ouachitas and the Ozarks and 161 animals released in northeast Louisiana and the Atchafalaya Basin—inland Louisiana.

This translocation has proved problematic to the two states trying to manage the populations. The federal government listed the Louisiana black bear (Ursus americanus luteolus) as a threatened sub-species in 1992, despite controversy over the genetic heritage of the animals. And researchers have debated whether to characterize the White River Refuge bears as closer to Minnesota black bears (Ursus americanus americanus) or to Louisiana black bears.

To determine the genetic relationships between the bear populations, the researchers examined the DNA of three populations of bears in Arkansas, two in Louisiana and one in Minnesota, examining a total of 82 bears.

They found that the White River Refuge bears and the Louisiana coastal bears demonstrated the most genetic distance from the others, indicating that their populations had been isolated from the others for longer. The genetic markers from the Ouachita, Ozark, inland Louisiana and Minnesota black bears showed that they were more closely related.

These findings fit with what wildlife biologists have suspected and should be the expected pattern based on historical accounts of the origins of bear populations in Arkansas and Louisiana, Smith said.