Biodiversity and Conservation

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● Biodiversity occurs not only in the species level, but also in the

macromolecular levels.

● Biodiversity as described by Edward Wilson is the combined diversity

at all levels of biological organisation.

● The most important forms of biodiversity are:

○ Genetic diversity (diversity at the genetic level)

○ Species diversity (diversity at the species level)

○ Ecological diversity (diversity at the ecosystem level)

● There are close to 1.5 million plants and animals that have to be

discovered and described. More species have been discovered in

temperate regions as compared to tropics.

● According to an estimate made by Robert May, global species

biodiversity is about 7 million.

● Of the total species discovered so far, 70% are animals and 22% are

plants. Of the animals, 70% are insects.

● India has 2.4% of the world’s land and 8.1% of the total species

diversity. According to May’s estimate, 78% of the biodiversity is still

to be discovered.

● Applying this to India’s biodiversity figures, there still is a scope for

discovery of over 1 lakh species of plants and 3 lakh species of

animals.

Patterns of Biodiversity

● Latitudinal gradients − The plants and animals are not distributed evenly

worldwide. The diversity of living forms decreases as we go from the equator

towards the poles. A huge amount of plants and animals are concentrated in the

tropical region because of the following reasons.

● Tropical environment is less seasonal and almost constant and

predictable as compared to temperate environment.

● Tropics receive the major part of the solar energy, which contributes

to great productivity.

● Speciation is dependent upon time. Tropical areas have remained

undisturbed for millions of years unlike temperate regions, which have

experienced frequent glaciations in the past.

● Species-Area relationships − Alexander von Humboldt observed that

biodiversity increases with increase in explored area. This relationship can be

given by,

log S = log C + Z log A

Where,

S = Species richness

A = Area

Z = Slope of the line (regression co-efficient)

C = Y-intercept

Value of Z is found to lie in the range of 0.1 to 0.2 for comparatively

smaller areas such as countries while for very large areas such as entire

continents, the slope of the line is much steeper with Z value lying from

0.6 to 1.2.

Importance of biodiversity & Loss of
Biodiversity

What is the importance of biodiversity on the Earth?

● There is no exact answer to this question, but experiments conducted

by many ecologists have demonstrated that a system with greater

biodiversity is more stable and has greater productivity.

● In the long run, biodiversity is related with overall health of our

ecosystem and survival of human race on the earth.

● Characteristics of a stable community:

○ It should not show much variation in productivity from year to

year.

○ It must be either resistant or resilient to occasional disturbances.

○ It must be resistant to invasion by alien species.

Loss of Biodiversity

● Due to human activities, the natural wealth is getting lost rapidly.

● The last 20 years have seen the loss of 27 species.

● Some of the causes of this loss are:

○ Habitat loss and fragmentation − This is the major cause for loss

of biodiversity. Habitat destruction is caused by human activities such as

deforestation and increasing pollution, leading to the loss of many plants

and animals.

○ Over-exploitation − Humans due to their greed and increased

exploitation of natural resources have contributed to the endangerment of

commercially important species of plants and animals. Example − Species

such as Steller’s sea cow and passenger pigeon have been extinct due to

over exploitation by humans.

○ Alien-species invasion − The unintentional or deliberate introduction

of alien species causes the declination of the indigenous species.

Example − Nile perch introduced in Lake Victoria led to the extinction of

more than 200 species of cichlid fish in the lake.

○ Co-extinction − When a plant or animal becomes extinct, another plant

or animal which is dependent on it in an obligatory way also becomes

extinct. Example − In case of plant-pollinator mutualism, the extinction of

one partner will eventually lead to the extinction of other also.

Biodiversity Conservation

● Biodiversity conservation is necessary because of the following

reasons:

○ Many commercially important products are obtained by nature

such as food, fibre, wood, and countless industrial products.

○ Certain activities and products cannot be accomplished without

the help of nature such as production of oxygen and pollination.

○ Intangible benefits such as aesthetic pleasure are derived from

nature.

○ Conserving the species we share our planet with and passing the

rich legacy of biodiversity to our future generations is our ethical

duty.

● Biodiversity can be conserved by:

○ In-situ conservation - In order to conserve biodiversity better,

some of the world’s biodiversity hotspots (with high degree of

biodiversity and endemism) have been identified and are

protected. In India, biosphere reserves, wildlife sanctuaries, and

national parks are built for this purpose.

○ Ex-situ conservation - The threatened species of plants and

animals are taken out of their habitats and are kept in special

settings as in zoological parks, botanical gardens, and wildlife

parks.

Nowadays, the gametes of endangered species can be preserved

viable by methods such as cryopreservation and can be fertilized

in-vitro followed by propagation through tissue culture methods.

Similarly, seeds can be preserved in seed banks.