ISC 12>CONTENT> UNIT 4> APPLICATIONS OF BIOLOGY> 2. BIODIVERSITY TODAY
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GENE POOL
- The total set of genes and alleles present in a population is known as gene pool.
- Populations that are separated from one another and do not interbreed will have separate gene pools.
- Depending on their environmental conditions and their history the gene pools of populations even within species can be quite different.
- A large gene pool indicates extensive genetic diversity.
- Gene pool increases when mutation occurs and survives.
- Gene pool decreases when the population size is significantly reduced.
GENETIC CONSERVATION
Conservation of genetic resources or all the varieties of genes present in different varieties of a species, that are likely to be employed for the improvement of domesticated plants.
The genetic material that is contained within the reproductive cells is called germplasm.
Importance of preserving the wild germplasm-
The genetic material that is contained within the reproductive cells is called germplasm.
Importance of preserving the wild germplasm-
- wild plants remain unprotected by man against predators, pests and diseases.
- wild plants adjust to unfavorable conditions.
- Wild plants bear useful genes for disease resistance, environmental stree etc.
GENETIC EROSION
The loss of genes from gene pool of some genetically uniform crop pplants is genetic erosion.
Causes of genetic erosion
Causes of genetic erosion
- Deforestation
- Urban expansion
- Shifting cultivation
- Environmental effects
GENE BANK
An institution where valuable plant materials likely to become irrevertrivably lost in the wild or cultivation is preserved in viable condition.
CRYOPRESERVATION
Preservation of organs, tissues and cells at very low temperature. (-196 degree celcius). At low temperatures the biological activity ceases, mitosis stops and no genetic change takes place.
Thus cryopreservation can increase the storage life of an organ or tissue. These organs can be transplanted whenever needed.
Thus cryopreservation can increase the storage life of an organ or tissue. These organs can be transplanted whenever needed.
BIODIVERSITY
- The variety of life in the world or in a particular habitat or ecosystem.
- Term coined by Walter G. Rosen in 1986.
- In our biosphere immense diversity (or heterogeneity) exists not only at the species level but at all levels of biological organisation ranging from macromolecules within cells to biomes.
- Biodiversity is the term popularised by the sociobiologist Edward Wilson to describe the combined diversity at all the levels of biological organisation
ORGANISATIONAL LEVELS OF BIODIVERSITY
- 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.
2. Species diversity:
- The diversity at the species level. For example, the Western Ghats have a greater amphibian species diversity than the Eastern Ghats.
3. 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 diversity than a Scandinavian country like Norway.
- Diversity at the level of community and ecosystem exists along 3 levels. It could be within-community diversity (alpha diversity), between-communities diversity (beta diversity) or diversity of the habitats over the total landscape or geographical area (gamma diversity).
STATUS OF BIODIVERSITY
- Since there are published records of all the species discovered and named, we know how many species in all have been recorded so far, but it is not easy to answer the question of how many species there are on earth.
- According to the IUCN (2004), the total number of plant and animal species described so far is slightly more than 1.5 million, but we have no clear idea of how many species are yet to be discovered and described.
- Estimates vary widely and many of them are only educated guesses. For many taxonomic groups, species inventories are more complete in temperate than in tropical countries.
- Considering that an overwhelmingly large proportion of the species waiting to be discovered are in the tropics, biologists make a statistical comparison of the temperate-tropical species richness of an exhaustively studied group of insects and extrapolate this ratio to other groups of animals and plants to come up with a gross estimate of the total number of species on earth.
- Some extreme estimates range from 20 to 50 million, but a more conservative and scientifically sound estimate made by Robert May places the global species diversity.
- More than 70 per cent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total. Among animals, insects are the most species-rich taxonomic group, making up more than 70 per cent of the total. That means, out of every 10 animals on this planet, 7 are insects
STATUS OF BIODIVERSITY : IN INDIA
- Although India has only 2.4 per cent of the world’s land area, its share of the global species diversity is an impressive 8.1 per cent. That is what makes our country one of the 12 mega diversity countries of the world. Nearly 45,000 species of plants and twice as many of animals have been recorded from India. How many living species are actually there waiting to be discovered and named? If we accept May’s global estimates, only 22 per cent of the total species have been recorded so far. Applying this proportion to India’s diversity figures, we estimate that there are probably more than 1,00,000 plant species and more than 3,00, 000 animal species yet to be discovered and described.
- IMPORTANCE OF BIODIVERSITY
LOSS OF BIODIVERSITY (EXTINCTION)
- SUSCEPTIBILITY TO EXTINCTION
Conservation of Biodiversity
Conservation is defined as the management of human use of the biosphere so that it may yield the greatest sustainable benefit to the present generation while maintaining its potential to meet the needs and aspirations of future generations
There are two basic strategy of biodiversity conservation
There are two basic strategy of biodiversity conservation
- In situ (on site)
- Ex situ (off site)
In situ conservation (on site)
1. National Park
A national park is a tract of land reserved and maintained by a national government solely for the welfare of the entire wild life in it.
Cultivation and grazing are not allowed in national parks.
Private ownership is not allowed.
There are at present 85 national parks in India.
A national park is a tract of land reserved and maintained by a national government solely for the welfare of the entire wild life in it.
Cultivation and grazing are not allowed in national parks.
Private ownership is not allowed.
There are at present 85 national parks in India.
2. Wild life sanctuary
A sanctuary is an area reserved for the conservation of animals only.
Operations such as procuring timber, forest products and private ownership is allowed provided they do not affect the animals.
There are at present 448 sanctuaries in India.
A sanctuary is an area reserved for the conservation of animals only.
Operations such as procuring timber, forest products and private ownership is allowed provided they do not affect the animals.
There are at present 448 sanctuaries in India.
3. Biosphere reserves
A biosphere reserve is a specified area in which multiple use of the land is permitted by dividing it into zones, each for a particular activity.
The concept of biosphere reserves has been evolved by UNESCO's Man and Biosphere Programme (MABP).
Role of Biosphere reserve-
A biosphere reserve preserves
a)wild population
b)life style of tribals
c) genetic resources of domesticated plants and animals.
It helps in
1)Conservation
2)Promotes economic development
3)Scientific research, monitoring and education.
A biosphere reserve is a specified area in which multiple use of the land is permitted by dividing it into zones, each for a particular activity.
The concept of biosphere reserves has been evolved by UNESCO's Man and Biosphere Programme (MABP).
Role of Biosphere reserve-
A biosphere reserve preserves
a)wild population
b)life style of tribals
c) genetic resources of domesticated plants and animals.
It helps in
1)Conservation
2)Promotes economic development
3)Scientific research, monitoring and education.
4. Sacred forest and sacred lakes
A traditional strategy for the protection of biodiversity has been in practice in India and some other Asian countries in the form of sacred forests.
These are forest patches of varying dimensions protected by tribal communities due to religious sanctity accorded to them.
Karnataka, Maharashtra, Kerala, Meghalaya etc. and are serving as refugee (an area in which a population of organisms can survive through a period of unfavourable conditions) for a number of rare, endangered and endemic taxa.
Similarly several water bodies (e.g., Khecheoprai lake in Sikkim) are declared sacred by people.
This indirectly leads to protection of aquatic flora and fauna.
A traditional strategy for the protection of biodiversity has been in practice in India and some other Asian countries in the form of sacred forests.
These are forest patches of varying dimensions protected by tribal communities due to religious sanctity accorded to them.
Karnataka, Maharashtra, Kerala, Meghalaya etc. and are serving as refugee (an area in which a population of organisms can survive through a period of unfavourable conditions) for a number of rare, endangered and endemic taxa.
Similarly several water bodies (e.g., Khecheoprai lake in Sikkim) are declared sacred by people.
This indirectly leads to protection of aquatic flora and fauna.
Ex- situ conservation (off site)
- Sacred plant and home garden
- Seed bank and gene bank
- Cryopreservation
- Botanical garden
- Zoological park
- Aquaria