13-10-2010, 09:18 PM
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Biodiversity
Biodiversity is the variety and differences among living organisms from all sources, including terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are a part.
It is virtually synonymous with “Life on earth”.
Biologists most often define "biological diversity" or "biodiversity" as the "totality of genes, species, and ecosystems of a region".
The biodiversity found on Earth today consists of many millions of distinct biological species, which is the product of nearly 3.5 billion years of evolution.
Levels of Biodiversity:
1) Genetic diversity:
It is a level of biodiversity that refers to the total number of genetic characteristics in the genetic makeup of a species.
It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary.
2) Species diversity:
It refers to the variety of species within a region.
Species diversity is an index that incorporates the number of species in an area and also their relative abundance.
It is generally a much more useful value than species richness.
3) Community and Ecosystem diversity:
Ecosystem diversity refers to the diversity of a place at the level of ecosystems. This has 3 perspective:
Alpha Diversity: Within community diversity. Alpha diversity refers to the diversity of organisms sharing the same Community/Habitat.
Beta Diversity: Between community diversity. It refers to the diversity of organisms sharing two habitat.
Gamma Diversity : Diversity of the habitat over the total landscape or geographical area is called gamma diversity
Values of Biodiversity:
Food: About 80,000 edible plants and about 90% of present day food crops have been domesticated from wild.
Drugs & Medicines: About 75% of world’s population depend on plants or plant extracts.
Fuel: Forests have been used since ages for fuel wood. Fossil fuels are also products of Biodiversity.
Social Value: Many of the plants like Tulsi, Lotus, Peepal etc are considered holy and sacred.
About 2.1 million species have been identified till date, while many more species are believed to exist.
According to UNEP estimate, approximately 9.0 – 52 million of species exist on Earth
India’s position is 10th in the world & 4th in Asia in terms of Plant diversity.