Tests on bighorn skulls and horns show greater genetic diversity in herds of older animals
Bighorn sheep living in decades past along Idaho’s Salmon River from Riggins to its East and Middle forks far upstream were more genetically diverse, and the different groups of sheep there were more connected with each other, compared to sheep populations of today.
A University of Idaho researcher made the determination by analyzing genetic samples taken from wild sheep skulls and horns that are part of the Carrey-Boggan Collection on display at the Jack O’Connor Hunting Heritage and Education Center at Lewiston.
Lisette Waits, a professor and researcher at the university’s College of Natural Resources at Moscow, led a team that compared the genetics of the sheep in the collection with samples taken from contemporary populations. They wanted to know how the genetic makeup of the sheep has changed over the years, particularly in response to severe population declines brought on by things like habitat degradation and disease introduced by domestic sheep.
“A lot of people look at these things on a wall and don’t realize they are actually really valuable to science,” Waits said of old horns and taxidermy specimens in general. “We can answer questions with that horn or part of the mount on a wall that we can’t answer if we sampled the wild animals that are present today.”
The herds of bighorn sheep along the Salmon River and its major tributaries offered a unique opportunity to make the genetic comparisons because they have not been mixed with sheep introduced from other areas, as they have been in other parts of Idaho and the West.
But the sheep there have suffered the same ills that have plagued bighorns across much of their range – the biggest being the introduction of pneumonia from domestic sheep herds, which resulted in a series of bighorn die-offs. Waits and her team speculated that when the populations declined, they may have lost some of the genetic variation that allows them to successfully adapt to changing environmental conditions.
To know for sure, they studied the DNA taken from the Carrey Collection. It was amassed by the late John Carrey, who spent his life in the same rough country along the Salmon River and its tributaries, where wild sheep still roam and once were as abundant as deer.
Carrey began collecting bighorn skulls as an adult. He eventually amassed dozens of them and recorded where each came from, who found it and when it was found. A few years ago Carrey’s friend, Doug Boggan of Pollock, acquired a large portion of the collection and allowed many of the skulls and horns to be displayed at the O’Connor Center named for the famed outdoor writer and sheep hunter from Lewiston.
Waits and her team found that sheep from the Carrey Collection did indeed have greater genetic diversity than those of today. While contemporary bands of wild sheep herds continue to intermix with other populations and exchange DNA, she found such mixing was more prevalent in the historic collection.
Waits said that mixing is good for maintaining genetic variations, but it also can be a problem if it leads to the spread of pneumonia from herd to herd.
Waits said the sheep of old “have more genetic variations, and things that humans have done on the landscape have caused the bighorn sheep to lose genetic variation, and that may influence their ability to survive in the future.”
The research also showed that the various groups of sheep along the Salmon River that are managed by the Idaho Fish and Game as distinct populations do appear to be genetically different from one another. Of all the populations today, the one living along the East Fork of the Salmon River near Challis is more isolated than other populations. There is evidence that sheep from that herd leave and mix with other groups, though the opposite rarely happens.
The Carrey-Boggan Collection can be viewed at the center located within Hells Gate State Park near Lewiston. It is open from 10 a.m. to 4 p.m. Tuesdays through Fridays and from 1-4 p.m. on Saturdays.