THE BIOGEOGRAPHY OF CANADIAN GRYLLOPTERA AND ORTHOPTERA

Abstract

AbstractThe saltatorial orthopteroid insects did not originate in North America. Five avenues of entry were utilized in migration from other parts of the world. These were: (1) ancestral forms migrated to this region in Pangaean times when all continents formed a single land mass; (2) later in time, taxa migrated from Europe when Eurasia and North America were still joined, or later via an Atlantic land bridge; (3) ancestral forms migrated northward from the Neotropical region before the separation of the two continents or, much later, when the two continents became rejoined; (4) later arriving taxa entered North America during the Pleistocene via a Beringian land bridge; (5) some species are very recent immigrants, either because of the activities of man or by migration into Canadian territory from the south.The fossil record is very incomplete. It indicates past climatic conditions, but is of limited assistance concerning extant taxa.Pleistocene glaciation had a profound effect upon the distribution of extant species. Many species were forced to move southward to escape the advancing ice. Some species probably were eliminated. It is clear that most of the extant species have migrated northward since the recession of the Wisconsin glacier.