BIODIVERSITY

AND
HOTSPOTS
 Abstract
Biodiversity is the very basis of human survival and economic well-
being, and encompasses all life forms, ecosystems and ecological
processes. The current estimates of the total number of species on
earth vary from 5 to more than 100 million, with a more conservative
figure of 13.6 million species. Of these, only 1.78 million species have
yet been described and awarded scientific names. Thus, our
knowledge of diversity is remarkably incomplete.
Biodiversity at any point in time is the balance between the rates of
speciation and extinction.Biodiversity is not uniformly distributed on
the earth and shows prominent latitudinal and altitudinal gradients.
At least five major mass extinctions have occurred in the past at
geologic-time boundaries. Studies indicate that we have entered into
the sixth phase of mass extinctions. In all ecosystem types, terrestrial,
freshwater and marine, species populations are declining.
The current rates of species extinction are 100–1000 times higher than
the background rate of 10−7 species/species year inferred from fossil
record. It is now in the order of 1,000 species per decade per million
species. Today we seem to be losing two to five species per hour from
tropical forests alone. This amounts to a loss of 16 m
populations/year or 1,800 populations/h. Major drivers for changes of
biodiversity in future, in decreasing rank of their impact are land use
change, climate change, N deposition, biotic exchange and
atmospheric loading of CO2.

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 TABLE OF CONTENT

S.NO TOPIC PAGE

NO.

1 ABSTRACT 1

2 INTRODUCTION 2

3 TYPES OF BIODIVERSITY 3

4 PATTERN OF BIODIVERSITY 6

5 IMPORTANCE OF SPECIES DIVERSITY 10

6 LOSS OF BIODIVERSITY 11

7 CAUSES OF BIODIVERSITY LOSSES 12

8 REASON OF BIODIVERSITY CONSERVATION 15

9 CONSERVATION OF BIODIVERSITY 17

10 CONCLUSION 21

11 BIBLIOGRAPHY 22
 INTRODUCTION
The occurrence of different types of genes, gene pools, species,
habitats, and ecosystem in a particular place and various parts
of earth is called biodiversity.

The term biodiversity was given by Edward Wilson.

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 Types of Biodiversity

Genetic Diversity
 It is the measure of variety in genetic information
contained in the organisms.
 It enables a population to adapt to its environment.
 For example, medicinal plant Rauwolfia vomitoria growing
in Himalayan ranges shows variation in potency and
concentration of the active chemical reserpine that it
produces.
 There are more than 50,000 genetically different strains of
rice and 1,000 varieties of mangoes in Indian.
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 Species diversity
 It is a measure of the variety of species and their relative
abundance present within a region.
 For example, the Western Ghats have a greater amphibian
species diversity than the Eastern Ghats.
Ecological diversity
 It is a measure of the diversity at community and
ecosystem levels. They represent the local, unite habitat
and regional components of species diversity.
 For example, ecological diversity is greater in India for to
presence of large number of ecosystem like deserts,
rainforests, coral reefs, wetlands, estuaries and alpine
meadow.

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Global species diversity
  According to the International Union for Conservation of
Nature and natural resources or IUCN (2004), the total
number of plant and animal species is over 1.5 million.
 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 are animals, while
plants account for about 22 per cent of the total.
 Amongst animals, insects comprise more than 70 per cent
that means, out if every 10 animals on the face of the
planet, 7 are insects.

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Patterns of biodiversity
Biodiversity is not uniform throughout the world because it is
affected by two factors – latitudinal gradients and species area
relationship.
1) Latitudinal gradients

 Biodiversity increases from poles to equators i.e. from high

to low latitude.
 Tropics (23.5°N to 23.5°S) have more species than
temperate or polar regions. For example, Columbia
located near the equator has 1400 species of birds while
New York (41°N) has 105 species and Greenland (71°N) has
only 56 species.
 Tropical rainforest of Amazon in South America possess
the greatest biodiversity on the earth with more think
40,000 species of plants, 3,000 of fishes 1,300 birds, 427 of
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427 of amphibians, 378 of reptiles and more than 1,25,000
invertebrates.

 Tropical rainforest of Amazon in South America possess

the greatest biodiversity on the earth with more thank
 40,000 species of plants, 3,000 of fishes 1,300 birds, 427 of
mammals.427 of amphibians, 378 of reptiles and more
than 1,25,000 invertebrates.

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 Temperate regions has been subjected to frequent
glaciations in the past but tropical regions remain
undisturbed. Therefore tropics had a longer evolutionary
time for the species classification.
 Temperate environment unlike the tropics are more
seasonal, less constant and unpredictable, resulting in less
niche specialisation and lesser species diversity.
 Tropics have greater solar energy exposure which contributes to
higher productivity and greater diversity.

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 German naturalist and geographer Alexander Von
Humboldt observed that within an region, species richness
increased with increasing explored area but up to a limit.
 The relationship between species richness and area for a
wide variety of taxa(like vascular plants, birds, bats and
freshwater fishes) appears as a rectangular hyperbola.
 On a logarithmic scale, the relationship is a straight line
described by the following equation:
log S = log C +Z log A
where, S = species richness
A = Area
Z = Slope of the line ( regression coefficient)
C = Y- intercept
 The value of Z lies in the range of 0.1-0.2 regardless of
taxonomic group or the region.
 However the analysis in a very large area like the whole
continent gives Z value that ranges from 0.6 to 1.2.

Importance of species diversity

 Ecologists believe that communities with more species tend to
be more stable than those with less species .This was confirmed
by David Tilman.
 Characteristics of stable community:
i. Productivity should not too much form year to year.
ii. It should be resistant to occasional natural and
artificial disturbance.
iii. It should be resistant to invasions by alien species.
 Importance of biodiversity for survival of species can be
explained by the ‘rivet popper hypothesis ’proposed by
Paul Ehrlich.
 This hypothesis assumes the ecosystem to be an airplane
and the species to be the rivets joining all parts together.
 If every passenger pops a rivet to take home (resulting in
species extinction), it may not affect the flight safety
initially (proper ecosystem functioning) but with time as
more rivets are removed the plane becomes dangerously
weak and fatal to the life of other species.

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Loss of biodiversity
 It is caused by overpopulation, urbanization,
industrialization.
  The colonisation of tropical Pacific Islands by humans led
to the extinction of more than 2,000 species of native
birds.
 At present, 31 per cent of gymnosperms, 32 per cent
amphibians, 12 percent of bird species and 23 percent of
mammals face the threat of extinction.
 Some recently extinct species are dodo ( Mauritius),
quagga (Africa), thylacine (Australia), Stellar's sea cow

Loss of biodiversity in a region may lead to

 Decrease in plant production.
 Less resistance to environment disturbances such as
drought.
 Increased variability in ecosystem processes like plants
productivity, water use pest and disease cycles.
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Causes of biodiversity losses

There are four major causes of biodiversity loss. These are also
known a ‘The Evil Quartel’
1. Habitat loss and fragmentation
 Destruction of habitat is the primary cause of extinction of
species.
 The tropical rainforest initially covered 14 per cent of the
land surface of earth, but now cover only 6 percent of land
area.
 The Amazon rainforest (called the lungs of the planet) is
being cut and cleared for cultivation of soya beans and for
conversions into grassland for raising beef cattle.
 When large-sized habitats are broken or fragmented due
to human settlements, building of roads, digging of canals,
etc .

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1.Over-exploitation
 When biological system is over exploited by man for the
natural resources, it results in degradation and extinction
of resources.

 For example, passenger pigeon and many marine fishes.

2. Exotic species invasions

 Some alien species when introduced unintentionally or
deliberately became invasive and cause harmful impact,
resulting in extinction of indigenous species.
 Nile perch, a large predator fish when introduced in Lake
Victoria, caused the extinction of an ecologically unique
species of Cichild fish in the lake.
 Invasive weed species like Parthenium (carrot grass),
Lantana and Eicchornia (water hyacinth)
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 Introduction of African catfish ( Clarias gariepinus ) for
aquaculture purposes is posing a threat to the indigenous
cat fishes of Indian rivers.
3. Co-extinction
 When a species become extinct, the plant and animal
species associated with it in an obligatory manner, also
become extinct.
 For example, if the host fish species becomes extinct, all
those parasites exclusively dependent on it, will also
become extinct; in plant-pollinator mutualism also,
extinction of one results in the extinction of the other.

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Reasons of biodiversity conservation

There are three main reasons for conserving the biodiversity
which have been classified into the following categories:
Narrowly utilitarian arguments
 Human beings derive direct economic benefits from the
nature, like food, firewood, fibre, construction material,
industrial products ( resins, gums, dyes, tannins, etc. ) and
medicinally important products.
 More that 25 per cent of the drugs are derived from plants
and about 25,000 species of plants are used by native
people as traditional medicines.

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Broadly utilitarian arguments
 Biodiversity plays a major role in maintaining and
sustaining supply of goods and services from various
species as well as ecological systems.
 The different ecological services provided are:
a) Amazon forest is estimated to contribute, 20 percent
of the total oxygen in the atmosphere on earth.
b) Ecosystem provides pollinators like bees, bumble
bees, birds and bats which pollinate plants to form
fruits and seeds.
c) Aesthetic pleasure like bird watching, spring flowers
in full bloom, walking through the thick forest, waking

up to bulbul's song etc. are some other benefits of

the ecosystem.

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 Conservation of Biodiversity

Biodiversity can be conserved by protecting its whole

ecosystem.
There are two basic approaches for conservation if
biodiversity.

In situ conservation (On site

conservation)
This approach involves protection of species in their natural
habitat.
 Biodiversity Hotspots
 These are regions of high levels of species richness
and high degree of endemism.
 Endemic species are species confined only to a
limited region.
 There are 34 Hotspots in the world.
 In India, the three hot spots are Western Ghats and
Sri Lanka, Indo – Burma and Himalaya.
 These reduce mass extinction by 30%.

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Protected Areas
 India has 14 biosphere reserves, 90 national parks and 448
wildlife sanctuaries.
 Jim Corbett National park was the first to be established in
India.

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Ramsar sites
  Ramsar sites are wetlands which are considered to be of
international importance.
 There are 26 Ramsar sites in India. Some of these are

chilika lake, Rudrasagar lake, etc

Sacred groves
These are forest patches set aside for worship. All the tree and
wildlife within are given protection by tribal people.

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Ex situ conservation
  This approach involves placing threatened animals and
plants in special care units for their protection.
 India has 35 botanical gardens and 275 zoological parks
where animals which has become extinct in wild are
maintained.
 By using cyropreservation technique sperms, eggs, animal
cells, can be stored for long periods in gene banks, seed
banks, etc.
 Plants are propagated in vitro using tissue culture

methods.

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Conclusion…
  The Earth summit was held in Rio de Janeiro in 1992,
which call led upon all nations to take appropriate
measures for conservation if biodiversity and sustainable
development.

 The World Summit on Sustainable development was held

in Johannesburg, South Africa in 2002 in which 190
countries pledged to reduce the current rate of diversity
loss at global, regional and local level by 2010.

 Biodiversity conservation tailored to changing climatic

conditions is not only necessary to help species and
habitats to adapt to change, but such action is also likely to
mitigate climate change. This is particularly true for
ecosystems that sequester and store carbon, such as
forests and peat swamps.

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Bibliography
 NCERT book class 12 biology
 https://www.natureandculture.org/biodiversity-
understanding-its-significance-and-conservation/
 https://serc.si.edu/research/research-topics/biodiversity-
conservation
 Wikipedia

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