In our biosphere immense diversity (or heterogeneity), exists not only at the species level but at all levels of biological organisation ranging from macromolecules within cells to biomes. Biodiversity is the term popularised by the sociobiologist Edward Wilson to describe the combined diversity at all the levels of biological organisation. The most important of them are-
(i) Genetic diversity.
(ii) Species diversity.
(iii) Ecological diversity.