Several geographical factors determine the biological richness of oceanic island and archipielagos. To investigate the importance of these factors we used data on flowering plants, ferns, land birds, beetles and butterflies of the native biota of the Macaronesian region (the archipielagos of the Azores, Madeira, the Canaries and Cape Verde). The five taxonomic groups vary in long-distance dispersal ability.
Three different analysis varying in level of approach were carried out: a Macaronesian or between-archipielagos approach, a Canarian or within-archipielago approach and finally a multiple island approach.
