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Biodiversity And Conservation

Biodiversity 3) There is more solar energy available in the tropics 
productivity is higher
• There are more than 20,000 species of ants, 3,00,000 species of ✓ Tropical Amazonian rain forest has greatest biodiversity on earth
beetles, 28,000 species of fishes and 20,000 species of orchids.
Species-Area relationships
• Biodiversity (= Heterogenity) is the term popularised by Edward
Wilson • Alexander von Humboldt explained Species-Area relationships
• He observed that within a region species richness increased with
Levels of Biodiversity increasing explored area, but only up to a limit
• Relationship graph is rectangular hyperbola
Genetic diversity
• Rauwolfia vomitoria is a medicinal plant, it shows genetic
diversity in terms of potency and concentration of chemical
reserpine, other examples are rice (50k strains) , mango (1000
varieties) etc.
Species diversity
• Western Ghats have a greater amphibian species diversity than
Z value
the Eastern Ghats
• Z lies in the range of 0.1 to 0.2
Ecological diversity: • Independent of the taxonomic group or the region
• India has a greater ecosystem diversity e.g. deserts, rain forests, • For large continent,
mangroves, coral reefs etc. ▪ Z value lies in the range of 0.6 to 1.2
▪ Shows steeper curve
How Many Species are there on Earth and How Many in India? ▪ Eg for frugivorous (fruit-eating) birds and mammals in
• Species inventories are more complete in temperate than in the tropical forests of different continents, Z=1.15,
tropical countries steeper curve (matlab birds aur mammal ki jyada variety
• Robert May places the global species diversity at about 7 kam area me milti hai)
million.
• According to May’s global estimates, only 22 per cent of the The importance of Species Diversity to the Ecosystem
total species have been recorded so far
• More than 70 % of all the species are animals, (Animals > • Communities with more species, generally, tend to be more
plants) stable than those with less species
• Insects are the most species-rich taxonomic group, out of every • Features of stable community
10 animals on this planet, 7 are insects ▪ do not show too much variation in productivity from year to
year;
▪ resistant or resilient to occasional disturbances
▪ resistant to invasions by alien species
• David Tilman performed long-term ecosystem experiments
using outdoor plots , showed :
▪ Plots with more species showed less year-to-year variation
in total biomass
• Among vertebrates fishes show maximum diversity ▪ Increased diversity contributed to higher productivity.
Fishes > Birds > Reptile > amphibian > mammal • Paul Ehrlich used rivet popper hypothesis; The hypothesis
• Among plants diversity is as follows suggests the importance of species richness in the
Fungi > Angiosperm > Algae > Pteridophytes maintenance of the ecosystem.
Airplane  ecosystem I Rivets  Species,
• Biologist are not sure about diversity amongst prokaryotes ,
because
Loss of Biodiversity
 Conventional taxonomic methods are not suitable for
• IUCN (International Union for conservation of nature) red
identifying microbial species
list documents recent extinctions include the dodo (Mauritius),
 many species are simply not culturable under laboratory
Quagga (Africa), Thylacine (Australia), Steller’s Sea Cow
conditions
(Russia) and three subspecies (Bali, Javan, Caspian) of tiger.
Patterns of Biodiversity • Mainly Amphibians and Gymnosperms are facing the threat of
extinction
Latitudinal gradients • we are currently witnessing ‘Sixth Mass Extinction’ current
Species diversity decreases as we move away from the equator species extinction rates are estimated to be 100 to 1,000 times
towards the poles, reasons: faster than earlier extinctions
1) Tropical latitudes have remained relatively undisturbed for • Loss of biodiversity in a region may lead to (a) decline in plant
millions → evolution → species diversification production, (b) lowered resistance to environmental
2) Tropical environments, unlike temperate ones, are less perturbations such as drought and (c) increased variability in
seasonal, more constant and predictable ecosystem processes
Causes of biodiversity losses: 2) Biosphere reserves
Four major causes (‘ The Evil Quartet’) • Large area, not limited by state legislation
• Tourism not permissible, Scientific research are carried out
Habitat loss and fragmentation: 3) National parks
• Amazon rain forest (‘lungs of the planet”) • Offers protection to entire plants , animals, landscape of region
▪ cleared for cultivating soya beans and for raising beef cattle • Highly restricted area, permission requires for entry
▪ used to cover more than 14 per cent of the earth’s land 4) Wildlife sanctuaries.
surface, now cover no more than 6 per cent • Mainly offers protection to wildlife
• Mammals (e.g., elephants) and birds are badly affected by • Less restriction, opens to public, activities like cattle grazing
fragmentation allowed
5) Sacred grove
Over-exploitation Regions that emphasised protection of nature as per religious and
cultural tradition.
Steller’s sea cow, passenger pigeon overexploited
by humans  now extinct Ex situ (off site) conservation

Alien species invasions • In this approach, threatened animals and plants are taken out
• Introduction of Nile perch into Lake Victoria  led to extinction from their natural habitat and placed in special setting where
of more than 200 species of cichlid fish they can be protected and given special care.
• Invasive weed species carrot grass (Parthenium), Lantana and • Ex situ conservation is done in:
water hyacinth (Eicchornia)  threat to environmental damage
• Catfishh Clarias gariepinus  threat to indigenous catfishes 1) Zoological parks,
2) Botanical gardens and
3) Wildlife safari parks
Co-extinctions 4) Cryopreservation
When a species becomes extinct, the plant and animal species 5)
associated with it in an obligatory way also become extinct. Also note :
When a host fish species becomes extinct, its unique assemblage The historic Convention on Biological Diversity (‘The Earth
of parasites also meets the same fate. Summit’) held in Rio de Janeiro in 1992, called upon all nations to
take appropriate measures for conservation of biodiversity and
Biodiversity conservation sustainable utilisation of its benefits.
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Why Should We Conserve Biodiversity?

Narrowly utilitarian arguments

• Humans derive countless direct economic benefits from nature
through firewood, fibre, construction material, medicine etc.
• Bioprospecting is exploring molecular, genetic and species-
level diversity for products of economic importance

Broadly utilitarian argument

Amazon forest produces 20 % of the total oxygen in the earth’s
Ecosystem provides pollination, pleasures of walking through
thick woods, watching spring flowers or a bulbul’s song etc

Ethical argument
A moral duty to care for well-being of other species

How do we conserve Biodiversity?

in situ (on site) conservation

1) Hot spots
• it is unrealistic and economically not feasible to conserve
biological wealth  Biodiversity “Hot Spots” regions have been
identified
• Biodiversity Hot spots are regions with very high levels of
species richness and high degree of endemism (that is, species
confined to that region and not found anywhere else)
• Total number of biodiversity hotspots in world: 34.
• Hot spots covering Indian regions : Western Ghats and Sri
Lanka, Indo-Burma and Himalaya
• Hot spots covers less than 2% of earth’s land but can reduce the
ongoing mass extinctions by almost 30 per cent.