Glacial Refugia
During the last ice age, much of Canada and the NWT was covered in ice. In order to survive, plants and animals shifted over time into areas that were ice-free, and established themselves in these refugia until the ice retreated. These areas are known as glacial refugia, and they are frequently “biodiversity hotspots” with a high diversity of plants and animals, rare species, unique species, and/or unique landforms. For example, refugia can contain the last remaining individuals of species that used to be wide-ranging but have now mostly disappeared. It is also possible that some populations, separated from the rest of their species within these refugia during the ice age, evolved increased genetic diversity. Sometimes they even evolved into completely new species. The physical features of the land are also different in areas that were not glaciated because they were not subject to these powerful forces that shaped entire landscapes.
The PAS Science Team is interested in identifying glacial refugia in the NWT due to their high conservation value. During the last glacial period, called the Wisconsinan, several ice sheets advanced and retreated, covering various parts of North America. The last glacial maximum in North America (when ice covered most of the continent) occurred about 21,400 calendar years ago. However, in the NWT (see map), the glacial maximum appears to have occurred 17,350 calendar years ago. This would be the age of the most recent refugia in the NWT, and of greatest conservation interest. This information is based on Dyke, A.S., Moore, A. and Robertson, L. 2003: Deglaciation of North America, Geological Survey of Canada Open File 1574.
