Fluctuations in the number of introduced and extinct species in Japan

Abstract

Changes in species richness of animals and plants in Japan were examined based on the compiled data on exotic, extinct ad/or endangered species of vertebrates (mammmals, reptiles, amphibians and pices), invertebrates (insects, crustaceans and molluscans) and vascular plants, respectively. The highest species richness of exotic species (EXT), as well extinct and/or endangered species (ENT), was found in vascular plants (1,581 EXT and 1,821 ENT among 7,000 native species), not in insects (466 EXT and 356 ENT among 32,000 native species). The highest species richness of ENT of animals was detected not in insects (356 spp) but in molluscans (584 spp) containing species richness one-tenth as that of insects in Japan. Taking into account that percentages of RED-listed species against species richness, as well percentages of endemic species included in ENT, were much higher for larger-sized vertebrates (mammals, amphibians, reptiles and pices), these EXT as invasive exotic species should have strongly negative effects on native communities/ecosystems. EXT < ENT for these taxa would accelerate to reshape native communities/ecosystems into novel ones.