Faunal patterns in tenebrionids (Coleoptera: Tenebrionidae) on the Tuscan Islands: The dominance of paleogeography over Recent geography

The tenebrionid fauna of the Tuscan Islands (Central Italy) is well known and is an ideal system for studying the role of current and historical factors in determining the biogeographical patterns in a complex archipelago. Cluster analyses, species-area relationships and Mantel tests were used to investigate the influence of current geography and Pleistocene connections with the mainland on the structure of insular communities. Current biogeographical similarity patterns fit both Pleistocene and Recent geography, but marked effects of Pleistocene geography appeared when the influence of Recent geography was removed. Thus, in contrast to more mobile insects, such as butterflies and chrysidids, tenebrionid colonization is likely to have occurred via land-bridges when the islands were connected to the mainland in the Pleistocene. The relict distributions of organisms with poor mobility should be of great concern to conservationists, because depletion of island populations cannot be balanced by new immigrations from mainland populations. The continued influence of man on the Tuscan Islands has adversely affected the natural environment, however, man made habitats may also be colonized and exploited by tenebrionids.