INSECTS OF WESTERN CANADA, WITH SPECIAL REFERENCE TO CERTAIN CARABIDAE (COLEOPTERA): PRESENT DISTRIBUTION PATTERNS AND THEIR ORIGINS

Abstract

AbstractMunroe (1956) summarized knowledge of the distribution patterns and history of the Canadian insect fauna; and a general synthesis beyond his conclusions is not yet possible. Results of studies on Nearctic Nebria taxa illustrate present distribution patterns and provide clues to the history of the montane fauna of western Canada. Nebria species and subspecies diversity is greatest in the Coast/Cascade Mountains just south of Canada and decreases northward. Major centers of endemism are located south of Canada, in the Coast/Cascade and southern Rocky Mountain systems, with minor centers found in western Alberta and the Queen Charlotte Islands. Species and subspecies vicariance patterns link Coast/Cascade and Rocky Mountain systems across the Okanagan lowland; and subspecies vicariance patterns link (1) Coast and Cascade mountains across Puget lowland/Georgia Strait and (2) central Canadian Rocky Mountains and Rocky Mountains of western Wyoming. These and other data presented on Nebria distribution patterns and faunal similarities among different mountain ranges and systems suggest that the present montane fauna of western Canada is derived from two source areas—one in the Coast/Cascade Mountain region, one in the Rocky Mountain region, each just south of the Canadian/U.S. border—which were separate and distinct during and after Wisconsinan time. Northern (e.g. Beringian) Wisconsinan refugia apparently did not contribute significantly to the present montane fauna.