It is estimated that the total number of species available on this planet may be close to 100 million (108), although earlier estimates give a figure of 10 million or 30 million. From such a large number of species, only about 1.4 million species of plants, animals and microorganisms have so far been given scientific names.

It has been shown that the diversity of fauna and flora varies in different ecosystems, habitats, geographical regions and also among different taxonomic groups. Following are some examples:

(i) Diversity is greater in terrestrial and fresh water species than in marine species.

(ii) In marine water, all the 33 living animal phyla are available, while only 17 are found on land and fresh waters.

(iii) Arthropoda among phyla and Insecta among arthropods have more species diversity than other groups; similarly nematodes, mites and fungi are highly diverse, the number of species approaching hundreds of thousands or millions.

For instance, 300 tree species occur in single - hectare plots in Peru, while only 700 tree species are found in whole of North America. In the same area, a single tree yielded 43 species of ants belonging to 26 genera, a level of diversity found in whole of British Isles.

Hyperdiversity in certain habitats or geographical regions or among certain taxonomic groups, depends on special adaptations which allow penetration of multiple niches by them. Following are some examples of these adaptations.

(i) Ants appear to expand due to fungistatic secretions, series-parallel work operations and a highly altruistic worker caste.

(ii) In insects, size, metamorphism and wings are adaptations that allowed development of hyperdiversity.