The impact of founder events and introductions on genetic variation in the muskox Ovibos moschatus

Abstract: The muskox is an ungulate that is well adapted to severe arctic conditions. Native populations are today found in northern Canada, the Canadian archipelago and on the northeastern coast of Greenland. Throughout its existence the muskox has been subject to many fluctuations in population size, both due to changing climate and intensive hunting during the hide trade in the 18- and 1900's. However, small refugia have persisted, allowing the muskox to increase in numbers again. In addition, introductions and translocations of the muskox around the Arctic have allowed the species to colonise new territories such as west Greenland and Norway. In 1971 five muskoxen left Norway and founded a population in Härjedalen, Sweden. Today (2008) the Swedish population consists of seven individuals. When trying to reinforce the genetic variation within the population one cow was mated with a captive Greenlandic bull, which resulted in a calf in 2006. To find out how muskox populations have been affected by sequential founder events muskox samples from the Canadian archipelago, east and west Greenland, Norway and Sweden were studied, using highly variable microsatellite markers. The result shows that the allelic variation follows the expectations of the founder events where Canada has the highest variation, followed by Greenland. However, the Swedish population has more genetic variation than Norway. This is explained by the contribution of two new alleles by the half-Greenlandic calf, indicating that one individual can make a large impact regarding the genetic variation. Also, the zoo population contains a higher degree of genetic variation than many of the introduced populations, revealing the importance of preserving the breeding programmes in zoos.