The different types of organisms found in an area is known as biodiversity or you can define it in a more accurately as ” the totality of genes, species, and ecosystems of a region”.

Biodiversity differ from place to place and dependence of human population has been enormously increased on biodiversity for their necessities.

The known and described number of species of all organisms on the earth is between 1.7 and 1.8 million which is fewer than 15 percent of the actual number. The predicted number of total species varies from 5 to 50 million averages at 14 million. About 61 per cent of the known species are insects. A large number of plant species and vertebrates are known. There are many more species that have not been described.

Biological diversity includes three hierarchical levels :

1. Genetic diversity

We know that each species, varying from bacteria to higher plants and animals, stores an immense amount of genetic information.

Genetic diversity refers to the variation of genes within species. The genetic diversity enables a population to adapt to its environment and to respond to natural selection. If a species has more genetic diversity, it can adapt better to the changed environmental conditions.

2. Species diversity

Species are distinct units of diversity, each play specific role in an ecosystem.

Species diversity refers to the variety of species within a region. Simplest measure of species diversity is species richness, I.e., the number of species per unit area. The no. Of species increases with the area of the site. Generally, greater the species richness, greater is the species diversity

3. Community and Ecosystem Diversity

Diversity at the level of. community and ecosystem has three perspectives. :-

◆ Alpha diversity ( within community diversity). Refers to the diversity of organism sharing the same habitat.

◆ Beta diversity ( between community diversity). Refers to species composition of community along environmental gradient.

◆ Gamma diversity ( diversity of the habitats over the total landscape or geographical area) Greater the dissimilarity between communities, higher is the beta diversity


source of food and Improved Varieties. ● Drugs and Medicines. ● Aesthetic and cultural Benefits. ● Ecosystem service


Habitat loss and fragmentation. ● Disturbance and pollution. ● Introduction of exotic Species. ● Extinction of species.


Conversation of biodiversity is now important for us. We know that ecosystem are undergoing change due to pollution, invasive species, over exploitation by humans, and climate change.

Most people are beginning to recognise that diversity at all levels – gene pool, species and biotic community is important and need conservation.

There are two basic strategies of biodiversity conservation, institute (on site) and exsitu ( off site).

° Insitu conservation strategies

The in situ strategies emphasis protection of total ecosystems. The in situ approach includes protection of a group of typical ecosystem through a network of protected areas.

Protected Areas

These are areas of land and sea, especially dedicated to the protection and maintenance of biological diversity. Examples are National parks and wildlife sanctuaries.

Biosphere Reserves

It is special category of protected areas of land and coastal environment where people are integral components of the system. There are 13 biospheres in india.

Sacred forests and sacred lakes

These are forest patches of varying dimensions protected by tribal community due to religious factors.

° Exsitu conversation strategies


In vitro conservation especially in liquid nitrogen at a temperature of -196℃. It is a storage of vegetatively propagated crops like potato.

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