(i) Genetic Bio- Diversity:
All forms of life on earth contain genes. Genes are carrier of hereditary characteristic from one generation to another.
" genetic diversity includes differences in the genetic makeup within same species". Within any given species there can be several differences in the colour, shape, size, resistance against diseases and resilience to survive under adverse environmental conditions. Such different characteristics within the same species are known as 'genetic biodiversity'. The species having large no of varieties-or races are considered as rich and more diverse in genetic makeup. The genetic diversity increases environment viability and contribute in the evolution of new species.
(ii) Species diversity:
It refers to the presence of variety of species within a specific region. Species diversity of a region is measured on the basis of two parameters these are "species richness" and "species evenness or equitability"
Species richness refers to the no of species per unit area.
Species evenness shows the evenness in no of individuals of that species. This can be understood by following example.
There are three sample areas:
Sample area 1: in this sample area there are three species of birds. One species has four individual and other two have one each. This sample area shows species richness.
Sample area 2: this sample area have three species of birds each having two individuals. This area shows species evenness and it is more diverse than sample area one.
Sample area 3: it has six individuals, two each from birds,mammals and insects. This sample is most diverse than the other two sample areas.
In the above example each has equal no of species but varying no of individual per species.
(iii) Ecosystem diversity:
It is defined as the diversity of habitats, communities, and ecological processes within the biosphere. It describes the no of niches, trophic levels and various ecological processes that sustain energy flow, food webs and the recycling of nutrients. The number of ecosystem may vary within a geographical region. It is measure of ecosystem diversity of a region.