‘Biodiversity means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.’ This is the single legally accepted definition of biodiversity adopted by the UN convention on Biological Diversity
In the simplest sense,
biodiversity may be defined as the sum total of species richness, i.e. the number of species of plants,
animals and microorganisms occurring in a given region, country, continent of the entire globe.
Genetic diversity (Diversity of genes within a species). Genetic diversity refers to the variation of genes
among the population and the individuals of the same species.
Species diversity (Diversity among species). It refers to the variety of species within a region, i.e. the
number of species per unit area at the site (species richness).
Ecosystem diversity (Diversity at the level of community/ecosystem). In an ecosystem there may exist
different landforms, each of which supports different but specific vegetations. Ecosystem diversity in
contrast to genetic and specific diversity is difficult to assess quantitatively since the boundaries of the
communities, which constitute the various sub-ecosystems are elusive.
Habitat diversity. It involves more than just the kind of communities and species- it depends on the
spatial arrangement of habitats across a large and on the fluxes of energy, nutrients, disturbances and
organisms across the area.
Ecological use three different terms for various practical measures of biodiversity:
Alpha diversity. It refers to diversity within a particular area, community or ecosystem, and is
measured by counting the number of texa within the ecosystem (usually species).
Beta diversity. It refers to species diversity between ecosystems and is measured by comparing
the number of texa that are unique to each of the ecosystems.
Gamma diversity. It is a measure of overall diversity for different ecosystems within a region.
IMPORTANCE OF BIODIVERSITY
The Benefits of Biodiversity to mankind are:
1. Ecological role of biodiversity
All species provide some kind of function to an ecosystem. They can capture and store energy, produce
organic material, decompose organic material, help to recycle water and nutrients throughout the
ecosystem, control erosion or pests, fix atmospheric gases, and help regulate climate. These
physiologically processes are important for ecosystem function and human survival.
Diverse is the ecosystem better able to withstand environmental stress and consequently is more
productive. The loss of a species is thus likely to decrease the ability of the system to maintain itself or to
recover from damage or disturbance. Just like a species with high genetic diversity, an ecosystem with
high biodiversity may have a greater chance of adapting to environmental change. In other words, the
more species comprising an ecosystem, the more stable the ecosystem is likely to be.
2. Economic role of biodiversity
For all humans, biodiversity is first a resource for daily life. One important part of biodiversity is crop
diversity, which is also called agrobiodiversity.
Most people see biodiversity as a reservoir of resources to be drawn upon for the manufacture of food,
pharmaceutical, and cosmetic products.
Some of the important economic commodities that biodiversity supplies to humankind are:
1.Modern agriculture: Biodiversoty is used as a source of material for breeding improved varieties,
and as biopesticides, biofertilizers etc.
2.Food: Crops, livestock, forestry and fish. Mangroves and coral reefs in coastal zone support
3. Medical drugs: Wild plant species have been used for medicinal purposes since before the
beginning of recorded history. For example, quinine comes from the cinchona tree (used to treat
malaria), digitalis from the foxglove plant (chronic heart trouble), and morphine from the poppy
plant (pain relief). According to the National cancer Institute, over 70% of the promising anti-
cancer drugs come from plants in the tropical rainforests. It is estimated that of the 2,50,000
known plants species, only 5,000 have been investigated for possible medical applications.
4.Industry: Fibers are used for clothing, wood for shelter, energy and various other uses.
Biodiversity may be a source of energy (such as biomass). Other industrial products are oils,
fragrances, dyes paper, waxes, rubber, latexes, resins, poisons, and cork, which all can be derived
from various plant species. Supplies from animal origin include wool, silk, fur, leather, lubricants
and waxes. Animals may also be used as a mode of transport.
3.Aesthetic and cultural benefits
Biodiversity has great aesthetic value. Examples of aesthetic value include eco-tourism, bird watching,
wildlife, gardening, etc. Eco-tourism is a source of economical wealth for many areas, such as many parks
and forests, where wild nature and animals are a source of beauty and joy for many people. Biodiversity is
also part of many cultural and religious beliefs. In many Indian villages and towns, plants like Ocimum
sanctum (Tulsi), Ficus religiosa (Pipal), and Prosopis cineraria (Khejri) and various other trees are
considered sacred and worshipped by the people. Several birds, animals and even snake have been
considered sacred. Also, we recognize several animals as symbols of national and heritage.
3. Scientific role of biodiversity
Biodiversity is important because each species can give scientists some clue as to how the life evolved
and will continue to evolve on Earth. In addition, biodiversity helps scientists understand how life
functions and the role of each species in sustaining ecosystems.
From above it is clear that the survival and well being of the present day human population, depends on
several substances obtained from plants and animals. The nutritional needs of mankind are also met by
wild and domesticated animal and plant species. Indeed, the biodiversity in wild and domesticated form is
the source for most of humanity’s food, medicine, clothing and housing, much of the cultural diversity,
and most of the intellectual and spiritual inspiration. It is, without doubt, the very basis of man’s being. It
is believed that 1/4th of the known biodiversity, which might be useful to mankind in one way or the
other, is in serious risk of extinction. This calls for an integrated approach for conserving global
Threats to Biodiversity
The loss of biological diversity is a global crisis. There is hardly any region on the Earth that is not facing
ecological catastrophes. Of the 1.7 million species known to inhibit the Earth (human are just one of
them), one third to one fourth is likely to extinct within the next few decades. Biological extinction has
been a natural phenomenon in geological history. But the rate of extinction was perhaps one species every
1000 years. But man’s intervention has speeded up extinction rates all the more. Between 1600 and 1500,
the rate of extinction went up to one species every 10 years. It is estimated that about 50 species are being
driven to extinction every year, bulk of them in tropical forest, due to human interference.
To highlight the legal status of rare species for the purpose of conservation, the International Union for
Conservation of Nature and Natural Resources (IUCN) has established the following five main
1.Extinct species that are no longer known to exist in the wild. Searches of localities where they
were once found and of other possible sites have failed to detect the species.
2.Endangered species that have a high likelihood of going extinct in the near future.
3.Vulnerable species that may become endangered in the near future because populations of the
species are decreasing in size throughout its range.
4.Rare species that have small total numbers of individuals often due to limited geographical
ranges or low population densities.
5.Insufficiently known species that probably belong to one of the conservation categories but are
not sufficiently well known to be assigned to a specific category.
These categories were named as Red list categories. The IUCN Red List is the catalogue of texa that are
facing the risk of extinction. This list aims to impart information about the urgency and scale of
conservation problems to the public, environmentalists and policy makers. On the global level, the IUCN
published Red Data Book, name given to the book dealing with threatened pants and animals of any
The IUCN, now known as World Conservation Union (WCU), in 2001 recognized nine Red List
Categories as Extinct (Ex), Extinct in wild (EW), Critically Endangered (CR), Endangered (EN),
Vulnerable (VU), Near Threatened (NT), Least Concern (LC), Data Deficient (DD) and Not Evaluated
(NE). The main purpose of the IUCN RED List is to catalogue and highlight those texa that are facing a
higher risk of global extinction (i.e. those listed Critically Endangered, Endangered and Vulnerable.
Reasons for extinction of Biodiversity
1. Destruction of habitat: The natural habitat may be destroyed by man for his settlement, grazing
grounds, agriculture, mining, industries, highway construction, drainage, dam building, etc. as a
consequence of this, the species must adapt to the changes, move elsewhere or may succumb to
predation, starvation or disease and eventually die. This is the most pervasive threat to birds,
mammals and plants affecting 89% of all threatened birds, 83% of the threatened animals
assessed. In our country, several rare butterfly species are facing extinction with the uncannily
swift habitat destruction of the Western Ghats. Of the 370 butterfly species available in the Ghats,
up to 70 are at the brink of extinction.
2. Hunting: From time immemorial, man has hunted for food. Commercially, wild animals are
hunted for their products such as hide and skin, tusk, antlers, fur meat, pharmaceuticals,
perfumes, cosmetics and decoration purposes. For example, in India, rhino is hunted for its horns,
tigers for bones and skin, musk deer for musk (have medicinal value), elephant for ivory, gharial
and crocodile for their skin, and jackal for thriving fur trade in Kashmir. One of the most
publicized commercial hunts in that of whale. The whalebone or ‘baleen’ is used to make combs
and other products.
Poaching of the Indian tiger has been risen because of the increasing demand from
pharmaceutical industries, which consume the bones of 100 tigers per year. Such huge demand
has been mat by poachers from India. Even the Project tiger Programme failed to check poaching
and resultantly the tigers have been almost disappeared from Ranthambore and Keoladeo national
parks. Smuggling of tiger bones and skins is a lucrative business. Hunting for sport is also a
factor for loss of wild animals.
3. Over exploitation: This is one of the main cause of the loss of not only economic species but
also biological ciriosities like the insectivorous and primitive species and other taxa needed for
teaching or laboratory (like Nepenthes, Gnetum, Psilotum, etc.). commercial exploitation of wild
plants has invariably causes their overuse and eventual destruction. This has been true in case of
Indian wild mango trees, which were turned into plywood as of the whales that were hunted for
tallow. Plants of medicinal value like Podophyllum hexandrum, Coptis teeta, Aconitum,
Disocorea deltoidea, Rauwolfia serpentine, Paphiopedilum druryi, etc., and horticultural plants
like orchids and rhododendrons come under the over-exploited category. Faunal losses have been
mainly because of over-exploitation. For instance, excessive harvesting of marine organisms such
as fish, mollusks, sea cows and sea turtles has resulted in extinction of these animals.
4. Collection for zoo and research: Animals and plants are collected throughout the world for zoo
and biological laboratories for study and research in science and medicine. For example, primates
such as monkey and chimpanzees are sacrificed for research as they have anatomical, genetic and
physiological similarities to human being.
5. Introduction of exotic species: Native species are subjected to competition for food and space
due to competition for food and space due to introduction of exotic species. For example,
introduction of goats and rabbits in the Pacific and Indian regions has resulted in destruction of
habitats of several plants, birds and reptiles.
6. Control of pest and predators: predator and pest control measures, generally kill predators that
are a component of balanced ecosystem and may also indiscriminately poison non-target species.
7. Pollution: Pollution alters the natural habitat. Water pollution especially injurious to the biotic
components of estuary and coastal ecosystem. Toxic wastes entering the water bodies disturb the
food chaion, and so to the aquatic ecosystems. Insecticides, pesticides, sulphur dioxide, nitrogen
oxides, acid rain, ozone depletion and global warming too, affect adversely the plant and animal
The impact of coastal pollution is also very important, it is seen that coral reefs are being
threatened by pollution from industrialization along the coast, oil transport and offshore mining.
Noise pollution is also the cause of wildlife extinction. According to a study Arctic whales are
seen on the verge of extinction as a result of increasing noise of ships, particularly ice breakers
8. Deforestation: One of the main causes for the loss of wildlife is population explosion and the
resultant deforestation. Deforestation mainly results from population settlement, shifting
cultivation, development projects, demand for fuel wood, demand of wood as a raw material for
many industries such as paper and pulp, match, veneer and plywood, furniture etc.
In the Country, the current rate of deforestation is 13,000 sq. km annually. If this rate of
deforestation continues, one can imagine the ultimate fate of our forest and biological richness. It
is presumed that in coming years, the global loss of biodiversity from deforestation alone would
be 100 species every day.
9. Other factors: Other ecological factors that may also contribute to the extinction of wildlife are
i. Distribution range – The smaller the range of distribution, the greater the threat of
ii. Degree of specialization – The more specialized an organism is, the more vulnerable it is
iii. Position of the organism in the food chain – The higher the position of the organism is in
food chain, the more susceptibility it becomes.
iv. Reproductive rate – Large organisms tend to produce fewer offspring at widely spaced
v. Outbreaks of diseases – it is also one of the major causes for the decline in wildlife
vi. Loss of gene flow – The individuals of plant and animal life may decline to the
significant levels as a result of loss of gene flow.
vii. Substitution – During the process of evolution an existing species may be replaced by
ecologically another one.
Convention on Biodiversity
The Convention on Biological Diversity (CBD) is an international legally-binding treaty with three main goals: conservation of biodiversity; sustainable use of biodiversity; fair and equitable sharing of the benefits arising from the use of genetic resources. Its overall objective is to encourage actions, which will lead to a sustainable future.
The conservation of biodiversity is a common concern of humankind. The Convention on Biological Diversity covers biodiversity at all levels: ecosystems, species and genetic resources. It also covers biotechnology, including through the Cartagena Protocol on Biosafety. In fact, it covers all possible domains that are directly or indirectly related to biodiversity and its role in development, ranging from science, politics and education to agriculture, business, culture and much more.
The CBD’s governing body is the Conference of the Parties (COP). This ultimate authority of all governments (or Parties) that have ratified the treaty meets every two years to review progress, set priorities and commit to work plans.
The Secretariat of the Convention on Biological Diversity (SCBD) is based in Montreal, Canada. Its main function is to assist governments in the implementation of the CBD and its programmes of work, to organize meetings, draft documents, and coordinate with other international organizations and collect and spread information. The Executive Secretary is the head of the Secretariat.