BIOGEOGRAPHY OF JACK PINE

Abstract

Interpretation of genetic variation associated with geographic origin must take into account the evolution and migratory history of the species being-studied. A literature survey was made to determine the probable origin of jack pine (pinus banksiana) and its migration from glacial refugia following the Wisconsin glacial maximum. Jack pine and contorta pine (Pinus contorta) became differentiated following cooling of the climate and crustal uplift in western North America in the late Tertiary. Modern hybrid swarms and introgression of jack pine and lodgepole pine (Pinus contorta var. lalifolia) east of the Rocky Mountains are of recent origin, dating from late post-glacial migration from the east and west respectively. Geological and paleobotanical evidence, particularly from fossil pollen depositions, indicate that jack pine survived glaciation in an extensive refugium centered on the Appalachian Highlands of eastern North America, and not in additional refugia south or west of the Great Lakes. This conclusion is consistent with the clinal pattern of geographic variation evident from genecological studies of the species.