02/08/2021
What is Biodiversity?
Biodiversity is the variety and variability of life on Earth. Biodiversity is typically a measure of variation at the genetic, species, and ecosystem level. Terrestrial biodiversity is usually greater near the equator, resulting from the warm climate and high primary productivity.
Conservation and sustainable use of biodiversity are fundamental to ecologically sustainable development. Biodiversity is part of our daily lives and livelihood and constitutes resources upon which families, communities, nations and future generations depend.
1. Levels of Biodiversity
Biodiversity is considered to exist at three levels: genetics, species, and ecosystems.
(i) Genetic diversity
It is concerned with the variation in genes within a particular species.
Genetic diversity allows species to adapt to changing environments.
This diversity aims to ensure that some species survive drastic changes and thus carry on desirable genes.
The survival of individuals ensures the survival of the population.
The genetic diversity gives us beautiful butterflies, roses, parakeets or coral in myriad hues, shapes and sizes.
(ii) Species diversity
It refers to the variety of living organisms on earth.
Species differ from one another, markedly in their genetic makeup, do not interbreed in nature.
Closely-related species, however, have in common much of their hereditary characteristics. For instance, about 98.4 per cent of the genes of humans and chimpanzees are the same.
The ratio of one species population over many organisms across all species in the given biome.
‘Zero’ would be infinite diversity, and ‘one’ represents only one species present.
(iii) Ecosystem/ Community diversity
This refers to the different types of habitats. A habitat is the cumulative factor of the climate, vegetation and geography of a region.
There are several kinds of habitats around the world. Corals, grasslands, wetland, desert, mangrove and tropical rain forests are examples of ecosystems.
Change in climatic conditions is accompanied by a change in vegetation as well. Each species adapts itself to a particular kind of environment.
As the environment changes, species best adapted to that environment becomes predominant. Thus the variety or diversity of species in the ecosystem is influenced by the nature of the ecosystem.
2. Measurement of Biodiversity
Two major components measure biodiversity:
(i) Species richness
It is the measure of the number of species found in a community
(a) Alpha diversity
It refers to the diversity within a particular area or ecosystem and is usually expressed by the number of species (i.e., species richness) in that ecosystem.
(b) Beta diversity
It is a comparison of diversity between ecosystems, usually measured as the change in the number of species between the ecosystems
(c) Gamma diversity
It is a measure of the overall diversity for the different ecosystems within a region.
(ii) Species evenness
It measures the proportion of species at a given site, e.g. low evenness indicates that a few species dominate the site.
3. Biodiversity and Food Web
The building blocks of plants, animals and humans are identical and are made of the four elements - carbon, oxygen, nitrogen and hydrogen.
These elements are present in the environment - in air, water and soil. However, only green plants can absorb nitrogen from the soil through their roots and use sunlight and water to produce energy through photosynthesis. They are known as producers.
Animals and humans, who have plants or other animals as their food, are known as consumers. The chain that links consumers to producers is called the food chain or web.
Every living creature is found in a food chain. There are several food chains, and they can be complex or simple, depending on the environment.
To cite some examples, grasshoppers eat grass and are eaten by frogs; snakes eat frogs and rodents.
Thus the importance of every creature in the web of life is evident. Tampering with the food chain only produces negative results, leading to the destruction of the species.
Every time a species becomes extinct, the chain is broken and many species, including humans, move closer to extinction.
4. Services provided by Biodiversity
Biodiversity provides several natural services for human beings
(i) Ecosystem services
Protection of water resources
Soils formation and protection
Nutrient storage and recycling
Pollution breakdown and absorption
Contribution to climate stability
Maintenance of ecosystems
Recovery from unpredictable events
(ii) Biological services
Food
Medicinal resources and pharmaceutical drugs
Wood products
Ornamental plants
Breeding stocks
Diversity in genes, species and ecosystems
(iii) Social services
Research, education and monitoring
Recreation and tourism
Cultural values
5. Causes for Biodiversity Loss
Loss of biodiversity occurs when either a particular species is destroyed, or the habitat essential for its survival is damaged. The latter is more common as habitat destruction is the inevitable fallout of development.
The extinction of species occurs when they are exploited for economic gain or hunted as sport or food. Extinction of species may also occur due to environmental reasons like ecological substitutions, biological factors, and pathological causes caused either by nature or man.
(i) Natural causes
floods,
earthquakes,
landslides,
rivalry among species,
lack of pollination and diseases.
(ii) Man-Made causes
Habitat destruction
Uncontrolled commercial exploitation
Hunting & poaching
Conversion of rich bio-diversity site for human settlement and industrial development
Extension of agriculture
Pollution
Filling up of wetlands
Destruction of coastal areas
6. Biodiversity conservation
Conservation of biological diversity leads to conservation of essential ecological diversity and preserve the continuity of food chains.
7. Modes of Conservation
(i) Ex-situ conservation: Conserving biodiversity outside the naturally occurring areas is known as ex situ conservation.
Here, animals are reared, or plants are cultivated like zoological parks or botanical gardens. Reintroducing an animal or plant into the habitat from where it has become extinct is another form of ex situ conservation.
For example, the Gangetic gharial has been reintroduced in Uttar Pradesh, Madhya Pradesh and Rajasthan where it had become extinct.
Seed banks, botanical, horticultural and recreational gardens are important centres for ex-situ conservation.
(ii) In-situ conservation: Conserving the animals and plants in their natural habitats is known as in-situ conservation. The established natural habitats are:
National parks
Sanctuaries
Biosphere reserves and
Reserved forests
Protected forests
Constraints in biodiversity conservation
Low priority for the conservation of living natural resources.
The exploitation of living natural resources for monetary gain.
Values and knowledge about the species and ecosystem are inadequate.
Unplanned urbanization and uncontrolled industrialization.
8. Botanical garden
Botanical garden refers to the scientifically planned collection of living trees, shrubs, herbs, climbers and other plants from various parts of the world.
Purpose of botanical gardens
To study taxonomy as well as the growth of plants.
To study the introduction and acclimatization process of exotic plants.
It acts as a germplasm collection
It helps in the development of new hybrids.
It augments conserving rare and threatened species.
9. ZOO
The zoo is an establishment, whether stationary or mobile, where captive animals are kept for exhibition to the public and includes a circus and rescue centres but does not include establishing a licensed dealer in captive animals - CZA.
The initial purpose of zoos was entertainment; over the decades, zoos have transformed into centres for wildlife conservation and environmental education.
Apart from saving individual animals, zoos play a role in species conservation (through captive breeding).
