Wolves ( Canis lupus ) and arctic foxes ( Alopex lagopus ) are the only canid species found throughout the mainland tundra and arctic islands of North America. Contrasting evolutionary histories, and the contemporary ecology of each species, have combined to produce their divergent population genetic characteristics. Arctic foxes are more variable than wolves, and both island and mainland fox populations possess similarly high...

Mate‐choice theory predicts different optimal mating systems depending on resource availability and habitat stability. Regions with limited resources are thought to promote monogamy. We tested predictions of monogamy in a social rodent, the hoary marmot ( Marmota caligata ), at the northern climatic extreme of its distribution. Mating systems, social structure and genetic relationships were investigated within and among neighb...

In many bat species, the opportunity for sperm competition or other mechanisms of post‐copulatory paternity biasing is thought to be great, due to the long delay between copulation and fertilization, demonstrated sperm storage capabilities, and observed promiscuity. We present the results of the first study to assess whether litters of big brown bats ( Eptesicus fuscus ) containing dizygotic twins share the same father. We sam...

The thinhorn sheep ( Ovis dalli ssp.) provides a rare example of a North American large mammal that occupies most of its native range and maintains close to ancestral population size. There are currently two recognized subspecies, Dall's sheep ( O. d. dalli ) and Stone's sheep ( O. d. stonei ), the validity of which remains uncertain. We investigated the spatial genetic structure of thinhorn sheep populations representing both...

This study characterizes population genetic structure among grey wolves ( Canis lupus ) in northwestern Canada, and discusses potential physical and biological determinants of this structure. Four hundred and ninety‐one grey wolves, from nine regions in the Yukon, Northwest Territories and British Columbia, were genotyped using nine microsatellite loci. Results indicate that wolf gene flow is reduced significantly across the M...

Fishers are mid‐sized forest carnivores indigenous to North America that experienced sharp population declines from the early 1800s through to the mid‐1900s. To evaluate levels of genetic variation within and subdivision among northern fisher populations 459 individuals were genotyped using 13 microsatellite loci. Genetic diversity was found to be slightly lower in re‐introduced populations than in adjacent indigenous populati...

Wolverines ( Gulo gulo ) are found in low densities throughout their circumpolar distribution. They are also potentially susceptible to human‐caused population fragmentation (development, recreation and fur harvesting). The combination of these factors has contributed to this species being listed as having either vulnerable or endangered status across much of its current range. The effects of inherently low densities and anthr...

We studied genetic structure in polar bear ( Ursus maritimus ) populations by typing a sample of 473 individuals spanning the species distribution at 16 highly variable microsatellite loci. No genetic discontinuities were found that would be consistent with evolutionarily significant periods of isolation between groups. Direct comparison of movement data and genetic data from the Canadian Arctic revealed a highly significant c...