EVOLUTION OF LAKE WHITEFISH (COREGONUS-CLUPEAFORMIS) IN NORTH-AMERICA DURING THE PLEISTOCENE - EVIDENCE FOR A NAHANNI GLACIAL REFUGE RACE IN THE NORTHERN CORDILLERA REGION

Lake whitefish (Coregonus clupeaformis) could have survived through (at least) the Illinoisan and Wisconsinan Pleistocene glacial maxima in an area in the vicinity of the present Nahanni National Park in the Northwest Territories of Canada according to the geological evidence. This possibility was addressed by an analysis of the genetic makeup of 43 lake whitefish populations in the Northwest Territories, the Yukon Territory, British Columbia, and Alberta. Populations in the lower Liard, Tetcela, Fraser, and upper Peace River systems as well as the headwaters of the Athabasca River were distinguished from both the Bering glacial refuge race populations inhabiting the Yukon and upper Liard River basins in the Yukon Territory and the Mississippi-Missouri glacial refuge race populations inhabiting most of the Northwest Territories, Alberta, and areas further to the east by a specific combination of electrophoretic mobility alleles. This evidence supports the hypothesis of the survival and subsequent dispersal of lake whitefish from a Nahanni glacial refugium. Possible dispersal routes and the limited extent of introgression among races are discussed.