Biodiversity is the variation of life at all levels of biological organization. In other words variability found in different forms of life like plants, animals and microorganisms and in their genes are called as biodiversity. It voluntarily integrates terresterial, aquatic and ecosystem diversity.  

There are three basic components of biodiversity:– (1) Genetic diversity, (2) Species diversity and (3) Ecological diversity. 

(d) Genetic diversity – Genetic diversity is related to the variations of genes within species. A single species might shows high diversity at the genetic level over its distributional range. For example, genetic variations shown by the medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges might be in terms of the potency and concentration of the active chemical (reserpine) that the plant produces. India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango. 

(e) Species diversity – The diversity at the species level is called species diversity. For example, the Western Ghats have a greater amphibian species diversity than Eastern Ghats. Similarly, taking example of plants, brinjal (Solanum melanogena), Potato (Solanum tuberosum) and tomato (Solanum lycopersicon) belong to the same genus Solanum but they all too differ at the species level. 

(f) Ecological diversity – The diversity at the ecosystem level is called ecological diversity. It is related to the different types of ecosystems, e.g., terrestrial (Deserts, rain forest, grass land, etc.) and aquatic (rivers, ponds, lakes, sea, etc.) ecosystems. 

Ecological diversity is of three types – Alpha (α), Beta (β) and Gamma (γ) diversity 

(i) Alpha diversity – It refers to the diversity of those organism which belongs to same community and habitat. 

(ii) Beta diversity – Diversity between diferent communities of same habitat is called beta diversity. If there is more heterogeneity in the habitats in a region or more dissimilarity between communities, there will be more beta diversity. 

(iii) Gamma diversity – Diversity at landscape level is called gamma diversity. It envolves both types of diversity – alpha and beta. It refers to the diversity of the habitats in the whole geographical region.