Biodiversity Types and Patterns

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 There are more than
 20,000 species of ants,
 3,00,000 species of beetles,
 28,000 species of fishes
 and nearly 20,000 species of orchids.

 Definition- Biodiversity can be defined as
the totality of genes, species and ecosystems
of a given region.
 This term was coined by EDWARD WILSON
 Diversity ranges from macromolecules to
biomes.
 Biodiversity can be studied at-
1. Genetic diversity
2. Species diversity
3. Ecological/Ecosystem diversity
For Good books for reference click on the picture
Or else see slide 52

1. GENETIC DIVERSITY
 Greater the genetic diversity among organisms of a species, more
sustenance it has against environmental perturbations.
 Genetically uniform populations are highly prone to disease harsh
environment.
 Rauwolfia vomitoria shows genetic variation in terms of concentration
and potency of chemical reserpine
 There are more than 50,000 varieties of rice and nearly 1000 varieties of
mangoes.

2. SPECIES DIVERSITY
 Important measures-
 1. Species richness: It refers to the number of
species per unit area.
 2. Species Evenness: It refers to the relative
abundance with which each species is
represented in an area.
 The variety and number of individuals
determine the level of diversity of an ecosystem.
 The Western Ghats have a greater diversity of
amphibian species than the Eastern Ghats.

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muralidhar-shingri

3. ECOLOGICAL DIVERSITY
 Ecological Diversity is related to species diversity.
 India has greater ecosystem diversity than any other
Scandinavian country.
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alidhar-shingri

 India has several biomes like alpine meadows,
rain forests, deserts, wetlands, mangroves…etc..
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GLOBAL BIODIVERSITY:
 According to the IUCN(2004) the total number
of plant and animal species is about 1.5
million.
 More than 70% of the species recorded are
animals and plants account for about 22%;
 70% of the animals are insects.
A more conservative and
scientifically sound
estimate has been made by
Robert May ;
it puts the global species
diversity at about seven
million.
International Union for Conservation of
Nature

 These estimates do not give any figure for
prokaryotes for the following reasons:
 1.The conventional taxonomic methods are not
sufficient for identifying these microbial species
 2. Many of these species cannot be cultured
under laboratory conditions.
 3. Biochemical and molecular biology techniques
would put their diversity into millions.

BIODIVERSITY IN INDIA
• India is one of the twelve mega biodiversity countries of the
world.
• India has only 2.4% of the land area of the world, it has 8.1%
of the global species biodiversity.
• There are about 45,000 species of plants and about 90,000-
1,00,000 species of animals.
• New species are yet to be discovered and named.
• Applying Robert May’s global estimate, only 22% of the total
species have been recorded,
India has probably more than 1,00,000 species of plants and
3,00,000 species of animals to be discovered and described.

PATTERNS OF BIODIVERSITY
 Biodiversity is not uniform throughout the world but
varies with latitude and altitude.
 Favourable environmental conditions favour
speciation and make it possible for a larger number of
species to exist there , i.e., biodiversity is more in such
areas than the others.
1. Latitudinal Gradients
2. Species-Area Relationship

1.Latitudinal Gradients
 Species diversity decreased from equator towards poles.
 The tropics harbor more species than temperate and polar
regions.
 Example- Colombia (near equator) has 1400 species of birds
whereas New York(41° N) has 105 species, Greenland(71 °
N) has 56 species and India(equator region) has 1200
species.

VARIATION OF SPECIES WITH LATITUDE
 The number of species of vascular plants in tropics is about
ten times more than that of temperate forests.
 Amazonian Rainforest has the greatest biodiversity on
earth.
 It has more than 40000 species of plants, 1,25,000 species of
insects, 300 species of fish, 427 of amphibian and 378 of
reptiles, 1300 species of birds and 427 of mammals.

2.Species-Area Relationship
 Alexander Von Humboldt has
observed that within a region,
species richness gets increased when
explored area is increased, but only
up to a limit.
 The relationship between species
richness and area for a number of
taxa like angiospermic plants, fresh
water fishes and birds is found to be
a rectangular hyperbola.

Graph showing Species-Area
Relationship
 The equation is described
by log S = log C + Z log A
 S – Species Richness
 Z – Slope of the line
(regression coefficient)
 A – Area
 C – y-intercept
• Ecologists have found that Z value ranges between 0.1 &
0.2 irrespective of the taxonomic group or the region.
• In very large area like continents, Z value ranges between
0.6 & 1.2.
For example, for frugivorous (fruit-eating) birds and
mammals in the tropical forests of different continents, the
slope is found to be 1.15. muralishingri@gmail.com

IMPORTANCE OF SPECIES DIVERSITY TO
ECOSYSTEM
 Ecologists believe that communities with more
species tend to be more stable than those with less
species.
Attributes of a stable community-
 1. It shall not show too much of variations in the
year-to-year productivity.
 2. It must be either resistant or resilient to seasonal
disturbances.
 3. It must be resistant also to alien species.

Feature of David Tilman’s ecology
experiments-
 1. The plots with more species showed
less year-to-year variation in the total
biomass.
 2. Plots with increased diversity showed
higher productivity.
 Hence, we realize that species richness
and diversity are essential for
ecosystem health as well as survival of
human race on earth.

One might ask Does it really matter to us
if a few species become extinct?
Would Western Ghats ecosystems be less
functional if one of its tree frog species is
lost forever?
How is our quality of life affected if, say,
instead of 20,000 we have only 15,000
species of ants on earth?

 There are no direct answers to such
näive questions but we can develop a
proper perspective through an analogy
(the ‘rivet popper hypothesis’) used by
Stanford ecologist Paul Ehrlich.
The rivet popper hypothesis:
In an airplane (ecosystem) all parts are joined together by
thousands of rivets (species).
If every passenger starts popping a rivet to take home
(species extinct),
it may not affect flight safety initially but as more and more
rivets are removed the plane becomes dangerously weak.
Further more which rivet is removed may also be
critical.Loss of rivets on the wings (key species) is obviously
a more serious threat to flight safety than loss of a few rivets
on the seats or windows inside the plane.

 Caused by Population, Urbanisation and
Industrialisation.
 The colonisation of tropical Pacific Islands by
human has led to the extinction of more than
2000 species of native birds.
 15,500 species are facing the threat all around.
 At now 31% gymnosperms, 32%amphibians,
12% bird species and 23% of mammals face
the threat.
LOSS OF BIO-DIVERSITY

Loss of bio-diversity in a region leads to or Effect
of biodiversity loss:
 (1) Decrease in plant production.
 (2) Less resistance to environmental disturbances
such as droughts.
 (3) increases variability in ecosystem processes
like plant productivity, water use, pest and
disease cycles etc.
For Good books for reference click on the picture
Or else see slide 52

Recent extinctions:
 The IUCN Red List
(2004) documents the
extinction of 784
species.
 Recent extinction
includes:
 Dodo (Mauritius).
 Quake (Africa)
 Thylacine (Australia)
 Stiller’s sea cow
(Russia)
 Dugong resembling
the steller’s sea cow

 Three subspecies of tiger (Bali, Java, Caspian

 Since the origin and diversification of life on earth there were five episodes
of mass extinction of species.
 The sixth mass Extinctions in progress now.
 How the’ sixth Extinction’ is different from the previous five extinctions.
 The current extinction rate is 100 to 1000 times faster.
 All others are pre-human period, this one is anthropogenic

CAUSES OF BIODIVERSITY LOSSES.
The present loss is all due to human activity
(anthropogenic)
There are four major causes (“The Evil Quartet”
is the sobriquet used to describe them) are as
follows:
1. Habitat loss and fragmentation
2. Over-exploitation
3. Alien species invasion
4. Co-extinction

I. HABITAT LOSS AND FRAGMENTATION
• Destruction of habitat is the primary cause of extinction of
species.
• The tropical rainforests initially covered 14% of land but
now only 6%.
• The Amazonian rain forest is called as ‘lungs of the planet‘
is being cut cleared for cultivating soya beans.
• When large sized habitats are broken or fragmented due to
human settlements, buildings of roads, digging of canals
etc.., animals requiring large territories and some animals
with migratory habitats are badly affected.

II. OVER-EXPLOITATION
• When ‘need’ turns to ‘greed’ it leads
to over-exploitation of natural
resources.
• Many species extinctions in the last
500 years (Stiller’s cow, passenger
pigeons) were due to over-
exploitation.
• Many marine fish populations
around the world are over harvested.

•The alien species became
invasive and cause decline or
extinction of indigenous species.
•Nile perch introduced into
Lake Victoria in east Africa led
to extinction of 200 species of
cichlid fish in the lake.
III. ALIEN SPECIES INVASIONS.

•Parthenium, (carrot
grass), Lantana, and
water hyacinth
(Eichornia) posed a
thread to indigenous
species.
•African cat fish
Clarias gariepinus for
aquaculture purposed
is posing a threat to
indigenous catfishes in
our rivers.

IV. CO-EXTINCTIONS
•When a species becomes extinct, the plant and animal
species associated with it an obligatory way also become
extinct.
•Extinction of Host species leads to extinction of the
parasite also.
•Co-evolved plant-pollinator mutualism where extinction
of one invariably lead to the extinction of the other.

BIODIVERSITY CONSERVATION:
Why should we conserve Biodiversity?
Reason for conservation biodiversity is
grouped into three categories.
1. Narrowly utilitarian.
2. Broadly utilitarian.
3. Ethical

1. Narrowly utilitarian
•Human derive countless direct economic benefits from
nature like Food (cereals, pulses, fruits), firewood, fiber,
construction material.
•Industrial products (tannins, lubricants, dyes, resins,
perfumes)
•Products of medicinal importance.
•More than 25% of the drugs are derived from plants and
more than 25,000 species of plants are used by natives for
medicine
•Bioprospecting: exploring molecular genetic and species-
level diversity for products of economic importance.

2. Broadly utilitarian
Biodiversity plays an important role
in maintaining and sustaining supply
of goods and services.
•Amazonian forest along produce
20% of oxygen during
photosynthesis.
•Pollinator layer:
bees, bumblebees, birds and bat that
pollinate the plant without which
seed cannot be produced by plants.
•Aesthetic pleasure we get from the
biodiversity.

3.Ethical
• There are thousands of
plants, animals and microbes
on this earth which are not
useless.
• Each one has some intrinsic
value even if it is not of any
economic value to us.
• It is therefore our moral duty
to ensure well-being of all the
living creatures for the
utilization.

CONSERVATION OF BIODIVERSITY /
How do we conserve biodiversity?
There are two basic approaches towards conservation of bio
diversity:
• In situ conservation
• Ex situ conservation

I. In situ conservation:
When we conserve and protect the whole ecosystem, its
biodiversity at all level is protected – we save the entire
forest to save the tiger. This approach is called in situ (on
site) conservation.
Hot spot in biodiversity is also regions of accelerated habitat
loss.
a) Biosphere reserves: Out of 425 biosphere reserves in the
world, 14 are in India.
Biodiversity hot spot:
regions with very high levels of species richness and high
degree of endemism.(species confined to that region and not
found anywhere else)
There are 34 hot spots in the world, of which three are in
India; namely Western Ghats and Sri Lanka, Indo-Burma
and Himalaya.

b) National parks and wildlife sanctuaries: India has 90
nationals parks and 448 wildlife sanctuaries.
c) Sacred groves: These are forest patches which were
venerated and given total protection. It includes a
number of rare, endangered and endemic species. Ex.
Western Ghats, Khasi and Jaintia Hills in Meghalaya.

II. Ex situ conservation:
Threatened animals and plants are taken out from their natural
habitat and placed in special setting where they can be protected and
given special care.
•Zoological Park, Botanical garden and Wildlife safari.
•Conservation of sperms, eggs, animal cells, tissues and embryos can
be stored for long period by cryopreservation technique (-196o C).
•Plants are propagated by using tissue culture methods called
micropropagation.
•Genetic strains are preserved in seed bank.

Convention on Biodiversity:
•“The earth Summit” held in Rio de Jeneiro in 1992 called
upon all nations to take appropriate measures for
conservation of biodiversity and sustainable utilization of
its benefits.
World Summit on Sustainable development held in 2002
in Johannesburg, South Africa, 190 countries pledged
their commitment to achieve by 2010 a significant
reduction in the current rate of biodiversity loss at global,
regional and local level.

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