. What are the Levels of Biodiversity.Explain


Best Answer

Biological diversity includes three hierarchical levels :

1. Genetic diversity

2. Species diversity

3. Community and ecosystem diversity.

1. Genetic diversity :  Genetic diversity refers to the variation of genes within species; the differences could be in alleles, in entire genes (the traits determining particular characteristics) or in chromosomal structures. The genetic diversity enables a population to adapt to its environment and to respond to natural selection.

The amount of genetic variation is the basis of speciation (evolution of new species). It has a key role in the maintenance of diversity at species and community levels. Genetic diversity of a community will be greater if there are many species.

A single species might show high diversity at the genetic level over its distributional range. The genetic variation 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 1000 varieties of mango.

Lower genetic diversity within a species or variety may be useful for uniformity in yield and higher yield but is prone to mass destruction by pests/pathogens.

2. Species diversity: Species are distinct units of diversity. 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 number of species increases with the area of the site. Another measure of diversity is species evenness which is number of individuals of different species.

In nature, both the number and kind of species, as well as the number of individuals per species vary, leading to greater diversity. For example, the Western Ghats have a greater amphibian species diversity than the Eastern Ghats in India.

3. Ecosystem diversity: Diversity at the level of community and ecosystem has three perspectives. Alpha diversity (within- community diversity), Beta diversity (between-community diversity). Diversity of the habitats over the total landscape or geographical area is called Gamma diversity.

Ecosystem diversity describes the number of niches, trophic levels and various ecological processes that sustain energy flow.

At the ecosystem level, India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway.

It has taken millions of years of evolution, to accumulate this rich diversity in nature, but we could lose all that wealth in less than two centuries if the present rates of species losses continue. Biodiversity and its conservation are now vital environmental issues of international concern as more and more people around the world begin to realize the critical importance of biodiversity for our survival and well- being on this planet.

 

 

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