Saturday, November 15, 2008

Biodiversity ---2

Loss of Biodiversity
The colonization of Tropical Island by humans is said to have led to extinction of more than 2,000 species of native birds. According the IUCN Red last (2004) 784 species of organisms are extinct in the last 5 years such as vertebrates (338), invertebrates (359), and 87 plants. Some recent examples are the dodo( Mauritius), quagga (Africa) thylacine (Australia).teller’s Sea Cow(Russia) and three subspecies( Bali, Javan, Caspian) of tiger. Recently in last 20 years 27 species disappeared.
Species facing the threat of Extinction are 12%of all bird species, 23% of all mammal species, 32% of all amphibian species and 31% of all gymnosperm species in the world.
Consequences of loss of Biodiversity
1. Decline in plant production
2. lowered persistence to environmental perturbations such as drought
3. Increased variability in certain ecosystems processes such as plant productivity, water use, and pest and disease cycles.
Causes of biodiversity losses
Habitat loss and fragmentation

This is the most important cause of extinction of plant and animals. When the habitat is lost the organisms either dies or moves to new habitats. Rain forest were covering 14% of earth’s land surface but now it is only 6%.The Amazon rain forest (it is so huge that it is called the ‘lungs of the planet’)millions of species cut and cleared for cultivating for growing Soya beans or for conversion to grasslands for raising beef cattle. Pollution is also one of the causes of threatening of many species. When large habitats are broken into small fragments due to various human activity, mammals and birds which needs large areas to live and certain animals with migratory habitats are badly affected, leading to populations declines.
Over-exploitation: Many species in the last 500 years (Steller’s sea cow, passenger pigeon) were extinct due to overexploitation by humans.
Alien species invasions: Sometimes introduction of alien species cause disappearance of native species.
· The Nile perch, an exotic predatory fish was introduced in Lake Victoria in east Africa resulted in elimination of more than 200 species of small Cichlid fish that were endemic in Lake Victoria.
· Invasive weed species like Carrot grass (Parthenium), Lantana threat posed to our native species.
· Water Hyacinth (Eicchornia) has resulted in Chogged Rivers and lakes which has threatened the survival of many aquatic species in lakes and ponds.
· The recent illegal introduction of the African catfish Clarias gariepinus for aquaculture posing a threat to the indigenous catfishes in our rivers.
Co-extinctions: When a species becomes extinct. The plant animal species associated with it an obligatory way also become extinct. When a host fish species becomes extinct its parasites also get extinct. Another example is the case of a coevolved plant- pollinator mutualism where extinction of one invariably leads to the extinction of the other.
Biodiversity Conservation
Why we should conserve Biodiversity?

a. The Narrowly utilitarian reasons: Human get benefits directly from nature such as Food-Cereals pulses fruits, firewood, fibers, construction material industrial products (tannins, lubricants, dyes, resins, perfumes) products of medicinal importance. More than 25% drugs sold in the market are derived from the plants and 25,000 species of plants are used by native people around the world.
b. The broadly utilitarian reasons: Biodiversity plays a major role in many ecosystems services that nature provides. Amazon forest is estimated to produce 20% of the total oxygen in the earth’s atmosphere. Pollination without (which plants cannot give us fruits or seeds)is another service, ecosystems provide through pollinators layer- bees, bumble bees, birds and bats.
c. Ethical: We also derive the aesthetic pleasures of walking through thick woods, watching spring flowers in full bloom or walking up to a bulbul’s song in the morning. This is our moral duty to care for their well being and pass on our biological legacy n good order to future generations.
How do we conserve Biodiversity?
Ex situ Conservation:
1. Hotspots
· To protect the organism biodiversity hot spots regions are identified. Hot spots are the richest and the most threatened reservoirs of plant and animal life. There are two criteria’s for determining the hot spot.
· Number of endemic species.
· Degree of threat, which is determined in terms of habitat loss.
· Initially 25 bio diversity hot spots were identified but now the total number of bio diversity hot spots in the world is 34.

.Three of these hot spots are Western Ghats and Sri Lanka, Indo- Burma and Eastern Himalayas.
· Though the area of bio diversity hot spots cover less than 2% of the total earth’s area but because of strict protection of these hot spots reduce the extinctions rate to 30%.
Bio sphere reserves are the protected area of land. In India there are 14 bio sphere reserves such as Nanda Devi, Sunder Vans. In India 19 National Parks and 448 Wild Life Centuries are present. In our country many plants and animals are sacred and worshiped by local peoples, so trees and wild life within are venerated and given total protection. Such sacred groves are found in Khasi and Jaintia hills in Meghalaya, Aravalli Hills of Rajasthan, and Western Ghats regions of M.P. In Meghalaya, the sacred groves are the last refuges for a large number of rare and threatened plants.
In this conservation threatened animals and plants are taken out from their natural habitat and placed in a place where they can be protected and given special care. Such as Zoological Parks, Botanical Garden, and wild life safari parks.
CRYOPRESERVATION –Gametes OF threatened species can be preserved in viable and fertile condition for long periods using CRYOPRESERVATION techniques. It is a technique by which plants and animals parts can be preserved in liquid nitrogen at a temperature of -196 0C
Eggs can be fertilized in vitro, and plants can be propagated tissue culture methods.
Seed Banks
Seeds of different genetic strains of commercially important plants can be kept for long periods in seed banks.

The historic Convention on Biological Diversity (‘The Earth Summit’) held in Rio de Janeiro in 1992., called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilization of its benefits. In a follow up, the World Summit on Sustainable Development held in Johensberg, South Africa, 190 countries pledged their commitment to achieve by 2010, to reduce the current rate of biodiversity loss at global, regional and local levels.

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