Contrasting levels of genetic differentiation among populations of wolverines (Gulo gulo) from northern Canada revealed by nuclear and mitochondrial loci Derrick E. Chappell 1 , Ronald A. Van Den Bussche 1, *, Julia Krizan 2 & Brent Patterson 2 1 Department of Zoology, Collection of Vertebrates, and Cooperative Fish and Wildlife Research Unit, Oklahoma State University, Stillwater, OK 74078, USA; 2 Department of Sustainable Development, Gov- ernment of Nunavut, Iqaluit, Nunavut, Canada XOA OHO; (*Author for correspondence: fax: 405-744-7824; e-mail: ravdb@okstate.edu) Received 19 March 2004; accepted 25 May 2004 Key words: conservation genetics, mtDNA structuring, wolverines Abstract Habitat loss, fragmentation, overharvest, and other anthropogenic factors have resulted in population and distribution declines for North American wolverines (Gulo gulo). Currently, wolverines east of the Hudson Bay are endangered and possibly extinct, whereas the status of wolverines throughout the remaining Holarctic is vulnerable. Three previous studies using nuclear loci have detected little to no significant structuring among wolverines sampled across northern Canada. Based on these results it has been sug- gested that wolverines in northern Canada represent a single, panmictic population. However, as has been shown in numerous studies, in cases of female site fidelity, it is possible to have demographically auton- omous populations even with male-biased gene flow. To better assess the genetic structure of wolverines in northern Canada, we examined nine microsatellite loci and DNA sequence variation from a 200 bp fragment of the mitochondrial (mtDNA) control region for 270 wolverines from nine collecting areas representing three regions of northern Canada. In agreement with previous studies, microsatellite analyses revealed a lack of significant population substructure (F ST ¼ 0.0004). However, analysis of molecular variance, comparisons of pairwise F ST values and nested-clade analysis of the mtDNA data revealed considerable genetic structuring among samples of wolverines from these three regions of northern Canada. These mitochondrial data provide evidence that wolverines in Canada are genetically structured due to female philopatry. The contrasting patterns of genetic differentiation based on nuclear and mitochondrial data highlight the importance of examining both nuclear and mitochondrial loci when attempting to elucidate patterns of genetic structure. Introduction Wolverines (Gulo gulo) are wide-ranging, solitary animals that occur at low population densities throughout tundra, taiga, and boreal forests of North America and Eurasia (Wilson 1982; Nowak 1991). Prior to human settlement in North Amer- ica, wolverines were distributed throughout Canada and Alaska with populations reaching as far south as Arizona and New Mexico (Hash 1987). However, due to habitat loss, fragmenta- tion, overharvest, and other anthropogenic factors associated with the arrival of human settlers, wolverines experienced severe population declines throughout much of their distribution (Wilson 1982). In North America, wolverines currently are distributed throughout western Canada and Alaska with individuals extending southward into remote areas of Washington, Oregon, California, Idaho, Montana, Wyoming, and Colorado (Banci Conservation Genetics 5: 759–767, 2004. Ó 2004 Kluwer Academic Publishers. Printed in the Netherlands. 759