Biodiversity and conservation

• there are more than 20,000 species of ants, 300000 species of beetles, 28,000 species of fishes and nearly 20,000 species of orchids.
• heterogeneity = biodiversity
• Biodiversity is the term popularised by the sociobiologist Edward Wilson
• 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.
• Western Ghats have a greater amphibian species diversity than the Eastern Ghats.
• The diversity keeps decreasing as we go from tropical regions to polar regions
• International Union for Conservation of Nature and Natural Resources (IUCN)
• the total number of plant and animal species described so far is slightly more than 1.5 million
• For many taxonomic groups, species inventories are more complete in temperate than in tropical countries
• 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 at about 7 million.
• More than 70 per cent of all the species recorded are animals, while plants are represented by no more than 22 per cent
• Among animals, insects are the most species-rich taxonomic group, making up more than 70 per cent of the total
• The number of fungi species in the world is more than the combined total of the species of fishes, amphibians, reptiles and mammals.
• estimates do not give any figures for prokaryotes
• conventional taxonomic methods are not suitable for identifying microbial species
• If we accept biochemical or molecular criteria for delineating species for this group, then prokaryotes diversity alone might run into millions.
• India has only 2.4 per cent of the world’s land area,
• India’s share of the global species diversity is an impressive 8.1 per cent.
• our country is 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
• May’s global estimates, only 22 per cent of the total species have been recorded so far
• 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 In India
• Patterns of biodiversity include latitudinal gradients and species-area relationships
• With very few exceptions, tropics (latitudinal range of 23.5° N to 23.5° S) harbour more species than temperate or polar areas.
• Colombia located near the equator has nearly 1,400 species of birds
• New York at 41° N has 105 species of birds
• Greenland at 71° N has only 56 species of birds
• India, with much of its land area in the tropical latitudes, has more than 1,200 species of birds.
• A forest in a tropical region like Equador has up to 10 times as many species of vascular plants as a forest of equal area in a temperate region like the Midwest of the USA.
• The largely tropical Amazonian rain forest in South America has the greatest biodiversity on earth- it is home to more than 40,000 species of plants, 3,000 of fishes, 1,300 of birds, 427 of mammals, 427 of amphibians, 378 of reptiles and of more than 1,25,000 invertebrates.
• in these Amazon rain forests there might be at least two million insect species waiting to be discovered and named.
• Speciation is generally a function of time, unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification
• Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable. Such constant environments promote niche specialisation and lead to a greater species diversity
• There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.
• German naturalist and geographer Alexander von Humboldt

  observed that within a region species richness increased with increasing explored area, but only up to a limit
• relation between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) turns out to be a rectangular hyperbola
• logS= logC+ZlogA

  where

  S= Species richness A= Area Z = slope of the line (regression

  coefficient)

  C = Y-intercept
• value of Z lies in the range of 0.1 to 0.2, regardless of the taxonomic group or the region
• species-area relationships among very large areas like the entire continents however, the slope of the line is much steeper (Z values in the range of 0.6 to 1.2)
• example, for frugivorous (fruit-eating) birds and mammals in the tropical forests of different continents, the slope is found to be 1.15.