HISTORICAL BIOGEOGRAPHY OF THE HOLARCTIC: AREA RELATIONSHIPS, ANCESTRAL AREAS, AND DISPERSAL OF NON-MARINE ANIMALS

Abstract — Based on published phylogenies for 73 groups of Holarctic non-marine animals, interrelationships between the four Holarctic infraregions (western and eastern Nearctic, western and eastern Palearctic) are examined. The study includes analysis of resolved area cladograms, ancestral areas and dispersal indicated by cladistic subordinateness. Area relationships reflecting present continental configurations (Nearctic vs. Palearctic) dominate the material to the extent that one might speak of a general Holarctic area pattern. Paleocontinental (western Nearctic+eastern Palearctic, western Palearctic+eastern Nearctic) and disjunct patterns are relatively more frequent among groups of higher taxonomic rank. The western Nearctic seems to have played a bigger role than the other infraregions as a center of origin. Two computer programs for constructing resolved area cladograms, viz., COMPONENT 1.5 and COMPONENT 2.0, are compared. The three standard assumptions for biogeographical analysis are compared and arguments are presented in favour of Assumption 0.