INSULAR BIOGEOGRAPHY OF SOUTHERN KURILE-I SLANDS - FAUNA FORMATION, SPECIES NUMBER AND COMPOSITION OF TERRESTRIAL VERTEBRATES AND CARABID BEETLES

The fauna of terrestrial vertebrates of the Southern Kurile Islands ha s some features of landbridge island faunas. Disproportionally poor fa unas of small islands and ''nested'' distribution of species indicate relaxation of initially common fauna of Hokkaido and the Kuriles after isolation of the latter, colonization being very limited. The origin of the carabid beetle fauna was associated with colonization and influ enced by habitat diversity. Presence of relict populations of some spe cies on the landbridge islands is evidence of influence of a previous landbridge connection. The species distribution on the landbridge isla nds is close to random but on the island chain of the Great Kurile Rei dge it is ''nested'' due to successive colonizations. Disproportionall y poor faunas of small landbridge islands may be caused by low habitat diversity if these islands while for the Great Ridge Islands it may b e a result both of isolation and of influence of environmental factors .