Evaluating the Genetic Distinctiveness of the Salmon River Drainage Bighorn Sheep and their Connectivity to Neighboring Populations

Scientific Disciplines
Biological Sciences - Terrestrial
University of Montana
bighorn sheep
salmon river
University of Idaho
genetic distinctiveness
Volume 17, No. 1-4

Evaluating the genetic distinctiveness of the salmon 
River drainage bighorn sheep and their connectivity to 
Neighboring populations
Nathan Borg,* University of Montana , Missoula Montana 59812 nathan.borg@umontana.edu
Lisette Waits, University of Idaho, Moscow, Idaho,  lwaits@uidaho.edu 
Pete Zager, Idaho Department of Fish and Game pete.zager@idfg.idaho.gov
Mike Mitchell, University of Montana, Missoula, Montana 59812, Michael.Mitchell@mso.umt.edu
Rocky mountain bighorn sheep (Ovis canadensis canadensis) were historically abundant 
in Idaho, but currently population levels remain low. Bighorn Sheep (BHS) in the Salmon 
River drainage are considered one of Idaho‚Äôs only remaining native sheep populations because 
they were never completely extirpated from their historic range. In addition, there has been 
little or no genetic influence via translocation of sheep from outside the drainage potentially 
making this BHS population genetically unique to Idaho. Contrastingly, surrounding 
populations to the west and east were extirpated or severely reduced and have subsequently 
been reintroduced or heavily augmented through use of translocations from Canada and 
several western states. There is presumably some degree of population connectivity between 
the Salmon River sheep and surrounding areas but to date, this has not been investigated 
using genetic data. To assess the genetic distinctiveness of Salmon River bighorns and their 
connectivity to other populations, we have collected genetic data from 15 nuclear DNA 
microsatellite loci for 256 BHS using blood and horn shaving samples across a 33,786-km2 
study area in central Idaho. The number of BHS genetic groups will be determined using 
Bayesian clustering algorithms, and the degree of connectivity between populations will be 
examined using Fst and assignment tests. Future directions include comparing radio-location 
data and genetic information to investigate structure/connectivity and potential for disease 
transmission of SRD bighorns as well as examining relationship between lamb productivity/
survival and genetic diversity/gene flow.