Genetic structure of rhinoceros auklets, Cerorhinca monocerata, breeding in British Columbia, Alaska, and Japan

The rhinoceros auklet (Cerorhinca monocerata) breeds on islands in the North Pacific from California to Japan. Breeding colonies are not evenly distributed along the coastline nor are population numbers similar throughout the range with approximately 50 % of the birds breeding in British Columbia, Canada (Rodway 1991). Like other puffins (tribe Fraterculini), rhinoceros auklets lay a single-egg clutch in an enclosed burrow, but unlike closely related species each parent provisions its offspring at most once per night with food loads consisting of fish and large invertebrates (Gaston and Dechesne 1996b; Takahashi et al. 1999). Comprehensive vital rate estimates are available over a 15-year period (1994–2008) from Triangle Island, which supports one of the larger colonies in British Columbia. Abstract Data from eight microsatellite markers screened in 246 rhinoceros auklets (Cerorhinca monocerata) from across the North Pacific revealed multiple genetic groups. The east (North America) to west (Japan) split was clearly evident in all analyses. Within the eastern Pacific, a minimum of three genetic groups are present. Surprisingly, rhinoceros auklets from Triangle Island, British Columbia, were genetically isolated from other nearby populations, including the breeding colony on Pine Island (~100 km to the east). A fourth genetic cluster (Chowiet Is) was detected using principal coordinate’s analysis; however, sample sizes were limited. Patterns of differentiation correspond to nonbreeding distributions with the eastern and western Pacific birds spending time off the west coast of North America and Japan, respectively, and may represent historical isolation in separate refugia during the Pleistocene