Habitat shifts to aquatic environment and back to dry land in the evolution of Coleoptera

The order Coleoptera (beetles) includes both terrestrial and aquatic species. The whole order as well as for all suborders (Archostemata, Myxophaga, Adephaga and Polyphaga) in ancetrally terrestrial. Habitat shifts occured in all suborders except Archostemata. A single shift to aquatic environment is probable in Myxophaga and Adephaga, multiple independent shifts from aquatic to terrestrial environments took place in Polyphaga. Multiple secondary habitat transitions back to terrestrial life style occured in Adephaga, Myxophaga and Polyphaga. However, phylogenetic relationships and/or detailed habitat requirements of adults and larvae are still unknown for many groups. That is why a reliable reconstruction of the evolution of habitat transitions between aquatic and terrestrial environment is still impossible in many cases. Key words: Coleoptera, habitat shifts, aquatic environment, terrestrial environment, evolution, phylogeny, biodiversity, morphology, adaptation