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Biodiversity and Conservation – CBSE Notes for Class 12 Biology

Biodiversity is a term used to describe the enormous variety of life on Earth. It can be used more specifically to refer to all of the species in one region or ecosystem. Biodiversity refers to every living thing, including plants, bacteria, animals, and humans.

Biodiversity is the term popularised by the socio-biologist Edward Wilson to describe the combined diversity at all the levels of biological organisation.

The most important of them are–

(i) Genetic diversity: 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 1,000 varieties of mango.

(ii) Species diversity: The diversity at the species level, for example, the Western Ghats have a greater amphibian species diversity than the Eastern Ghats.

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

Patterns of Biodiversity

Darwin noticed three distinctive patterns of biological diversity:

(1) Species vary globally

(2) Species vary locally

(3) Species vary over time

The importance of Species Diversity to the Ecosystem

Communities with more species, generally, tend to be more stable than those with less species. A stable community should not show too much variation in productivity from year to year. David Tilman found that plots with more species showed less year-to-year variation in total biomass and increased diversity contributed to higher productivity.

According to the rivet popper hypothesis, in an airplane (ecosystem) all parts are joined together using thousands of rivets (species). If every passenger travelling in airplane starts popping a rivet to take home (causing a species to become extinct), it may not affect flight safety (proper functioning of the ecosystem) initially, but as more and more rivets are removed, the plane becomes dangerously weak over a period of time.

Loss of rivets on the wings is more serious threat to flight safety than loss of a few rivets on the seats or windows inside the plane.

Loss of Biodiversity

The colonization of tropical Pacific Islands by humans is said to have led to the extinction of more than 2,000 species of native bird.

The IUCN Red List (2004) documents the extinction of 784 species.

Some examples of recent extinctions include the dodo (Mauritius), quagga (Africa), thylacine (Australia), Steller’s Sea Cow (Russia) and three subspecies (Bali, Javan, Caspian) of tiger.

Biodiversity Conservation

Biodiversity conservation refers to the protection, preservation, and management of ecosystems and natural habitats and ensuring that they are healthy and functional.

What is Loss of Biodiversity?

A number of factors like pollution, erosion, evolution, urbanization, industrialization, population, and depletion lead to the loss of biodiversity.

Loss of biodiversity is very harmful to the ecosystem as it indicates either loss of species, or reduction of species in a natural habitat, or both of them on a global level.

Loss of biodiversity has a poor impact on the ecosystem. Loss of biodiversity directly impacts the ecosystem and food chains in it. It affects agriculture and weakens the resistance to natural disasters like floods, drought, etc.

How do we conserve Biodiversity?

Two types of methods are employed to conserve biodiversity. They are- In situ conservation and Ex-situ conservation.

  • In situ Conservation: In Situ Conservation refers to the preservation and protection of the species in their natural habitat. It means the conservation of genetic resources in natural populations of plant or animal species. In situ conservation involves the management of biodiversity in the same area where it is found.
  • Ex Situ Conservation: Ex Situ Conservation means conservation of life outside their natural habitat or place of occurrence. It is the method in which part of the population or the entire endangered species is taken from its natural habitat which is threatened and breeding and maintaining of these species take place in artificial ecosystems. These artificial ecosystems could be zoos, nurseries, botanical gardens, etc. The living environments are altered in these conservation sites, so there are fewer survival struggles like scarcity of food, water, or space.
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