MITOCHONDRIAL-DNA VARIATION AND GENETIC-POPULATION STRUCTURE IN ROCKY-MOUNTAIN BIGHORN SHEEP (OVIS-CANADENSIS CANADENSIS)

Mitochondrial-DNA (mtDNA) variation in Rocky Mountain bighorn sheep wa s assessed to determine relationships among populations and the useful ness of mtDNA analysis for the conservation of bighorn sheep. Phylogeo graphic analysis revealed relatively divergent mtDNA haplotypes within herds and several geographically widespread haplotypes. This suggeste d that gene flow has occurred on a regional scale at some time in the past and that populations have not been subdivided by long-term biogeo graphic barriers. Nonetheless, significant differentiation in mtDNA-ha plotype frequencies among herds suggested that little gene flow curren tly exists among populations. Failure to recognize that historical (ph ylogeographic) and current population structure may not be concordant could lead to erroneous conclusions and conservation strategies.