Tiêu đề Biodiversity and Conservation 4.0.pdf ✅

Biodiversity and Conservation 1 3 Biodiversity and Conservation Biodiversity • Term given by Edward Wilson. • Combined diversity at all the levels of biological organization. The biodiversity can be studied at three levels. (1) Genetic Diversity (2) Species Diversity (3) Community and Ecosystem Diversity (1) Genetic Diversity: • A species show high diversity at gene level over it's distributional range. For ex. Medicinal plant Rauwolfia vomitoria growing in Himalayan range show diversity in synthesis of chemical reserpine in concentration and potential. • India has more than 50,000 genetically different strains of rice and 1000 varieties of mango. (2) Species Diversity: • Diversity at species level. • Generally, greater the species richness, greater is the species diversity. However, number of individuals among the species may also vary, resulting into differences in evenness or equitability in diversity. (3) Ecological or Ecosystem Diversity: • Diversity at ecosystem and community level. ex. India have diverse kind of ecosystem like desert, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows, than the Norway. Fig. Three perspectives of diversity: alpha, beta and gamma diversity.
2 Biodiversity and Conservation Magnitude of Biodiversity in World and India: • According to IUCN (2004) the total number of species of plants and animals described so far is slightly more than 1.5 million. • Scientists have calulated that the total number of species in the world ranges from 20 to 50 million. • Robert may, with more conservative and scientifically sould estimate, places the number of global species diversity of about 7 miillion. • According to currently available inventories of earth's biodiversity- 70% of all species is of animals. 22% of all species is of plants species (Algae, Bryophytes, Pteridophytes, Gymnosperms and Angiosperms) • Among animals, insects are most species rich (number of species) constituting 70% of total animal species. i.e., from every 10 animals, 7 are insects • Prokaryotes are not counted in global biodiversity as the number of prokaryotic species in not known, conventional taxonomic methods are not suitable for identifying them and many species are not culturable under laboratory conditions. → Biodiversity in India: • India share 2.4% of world land area but share global species diversity of 8.1% which make India one of the 12 mega diversity countries of world. India has 45000 species of plants and twice the number of species of animals and many more yet to be identified and discovered. • According to Robert Mays global estimates, only 22% of the total species have been recorded so far. Applying this proportion to India more than 1,00,000 plant and 3,00,000 animal species yet to be discovered and described. • The most biodiversity rich zone are Western Ghat and North East Himalaya account for 4% and 5.2% of geographical area respectively. • A very high number of Amphibian species are endemic to western ghat. • Biological diversity in ecosystems like deep oceans, wetlands, lakes and habitats like tree canopy and soil of tropical rain forest in India yet to be explored.

4 Biodiversity and Conservation • Generally the value of Z-line is in range of 0.1 to 0.2 regard less of taxonomic group or region. (whether it is the plants in Britain, birds in California or molluscs in New York state, the slopes of the regression line are amazingly similar). But, if you analyse the species-area relationships among very large areas like the entire continents, you will find that the slope of the line to be much steeper (Z values in the range of 0.6 to 1.2). Importance of Species Diversity to the Ecosystem • The number of species in a community is important for an ecosystem. It is believes that communities with more species are more stable and with less species are less stable. • A stable community mean- • Not show to much variation in productivity year to year. • It must be resistant (resilient) to occasional disturbances (Natural or Man made). • It must also be resistant to invasions by alien species. • Less seasonal variations. • How these attributes are linked to species richness in a community? According to David Tilman's long term ecosystem experiment using outdoor plots concluded that plots with more species shows less year to year variation in total biomass and increased diversity contributed to higher productivity. • Rich biodiversity is not only essential for ecosystem health, but also necessary for survival of human race on this planet. • How a species extinction anywhere on this planet affect the human race is explained by Stanford ecologist Paul Ehrlich by Rivet Popper Hypothesis. • He compare aeroplane as ecosystem joined together by thousands of rivets as species. If passengers travelling in it starts popping a rivet to take home (causing a species to become extinct) it may not affect flight safety (proper functioning of ecosystem) initially, but as more and more rivets are removed, the plane become dangerously weak over a period of time.