Global biodiversity much less than previously thought

London, June 10: Scientists have discovered that the count of species that share the planet with us is only 5.5 million, and not more than 30 million, as an earlier study quoted.

The error is attributed to arthropods, a phylum that includes insects and spiders. The global figure of over 30 million species was suggested in 1982 by Terry Erwin at the Smithsonian Institution in Washington DC - he took into account 163 species of beetle on one tropical tree, multiplied it by number of trees globally and scaled up the result to take into account the fact that beetles make up around 40 per cent of arthropod species.

According to New Scientist, now Andrew Hamilton of the University of Melbourne, Australia, has obtained a revised estimate using observations of 434 beetle species on 56 tree species in Papua New Guinea. He concludes with 90 per cent certainty that there are between 2.5 and 3.7 million arthropod species.

Bacteria were not included in either estimate as they are hard to separate into species.

Corey Bradshaw at the University of Adelaide, Australia, says that Erwin's figure of 30 million was unrealistic and conservative but so was Hamilton's because local geographical and ecological factors play a role in affecting biodiversity.

Margie Mayfield of the University of Queensland, Australia on the other hand, calls Hamilton's estimate "perfectly reasonable".

Copyright Asian News International/