Genetic diversity and management of Nearctic rock ptarmigan (Lagopus mutus)

Though the rock ptarmigan, Lagopus mutus (Montin, 1776), is a relatively common breeding bird in arctic regions worldwide, several Nearctic insular populations have become extinct or threatened in the past 250 years. In this study, we use patterns of DNA sequence variation in the mitochondrial control region and a nuclear intron (GAPDH) to reexamine the evolutionary history of Nearctic rock ptarmigan populations as a basis for conservation and management. The extent of genetic diversity within currently recognized subspecies varies widely, with many nonmigratory insular subspecies genetically invariant and continental subspecies moderately diverse. Our analyses suggest at least six evolutionarily significant units (ESUs) in the Nearctic and Iceland, four of which correspond to recognized subspecies: Lagopus mutus evermanni (Elliot, 1896) on Attu I., Alaska, Lagopus mutus welchi (Brewster, 1885) on Newfoundland, Lagopus mutus rupestris (Gmelin, 1789) in the Canadian Arctic, and Lagopus mutus islandorum (Faber, 1822) on Iceland. A fifth ESU comprises three central Aleutian subspecies. The remaining subspecies of the Aleutian archipelago, along with Lagopus mutus nelsoni (Stejneger, 1884) of mainland Alaska and Lagopus mutus captus (Peters, 1934) of Ellesmere I., Nunavut, constitute a sixth ESU, which we further subdivide into three management units based on patterns of genetic substructuring and geographic barriers to immigration.