An Outline of Materials for a Postglacial Bioclimatic History of Keewatin, Northwest Territories, Canada

摘要

Recognition of broad relationships between climate and the geographical range of plant species is based upon understanding of the ecological principles governing the response of the individual species to environment, in turn the result of physiological adaptations and evolutionary history. During the periods of glaciation, at least the Wisconsin glaciation, the Arctic flora apparently survived principally north of the ice in refugia along the north slope of the Brooks Range and the extreme Western Islands, and the boreal flora survived to the south of the ice. The Tertiary flora of the Arctic, known from fossil evidence, indicates that at this period a climate milder than at present (and much milder than the subsequent Pleistocene) extended far to the north, permitting forest growth into at least certain parts of the southern half of the Arctic Archipelago. Retreat of the Wisconsin ice permitted both arctic and boreal species to migrate into the areas they occupy today. In these areas there is now a wide variety of evidence indicating that there was a period of rather marked genetic differentiation (during the glaciations) followed by subsequent hybridization and intermingling of species and varieties. This is interpreted to mean that species were often split into two populations by the advancing ice. (Author)