- Word “biodiversity” is a contraction of the term “biological diversity” in 1995.
- Definition – The variety of plant and animal life in the world or in a particular habitat, a high level of which is usually considered to be important and desirable.
- In other words, Biodiversity or Biological diversity includes all the different plants, animals and microorganisms, the genes they contain and the ecosystems of which they form a part.
- India is recognized as one of the mega-diverse countries, rich in biodiversity and associated traditional knowledge. We have 7-8% of species of the world and that too just on 2.4% of the world’s land.
Levels of Biodiversity
- Biodiversity is considered to exist at 3 levels – genetic, species and ecosystems.
- It is a variation in genes within a particular species.
- A single species might show high diversity at the genetic level [E.g. Man: Chinese, Indian American, African, etc.]. India has more than 50,000 genetically different strains of rice and 1,000 varieties of mango.
- It is the total number of genetic characteristics in the genetic makeup of a species.
- It allows species to adapt to a changing environment.
- It ensures that some species survive drastic changes and thus carry on the desirable genes(just like what they say in movie “Lucy”, carrying information).
- The beautiful butterflies, roses, parakeets or coral in a myriad hue, shapes, and sizes are the result of Biodiversity.
- It is the variety of living organisms on earth
- Species have different genes and they do not interbreed in nature.
- Closely-related species have many common hereditary characteristics.
o For example – about 98.4% of the genes of humans and chimpanzees are the same.
- “Zero” means infinite diversity and “one” represents only one species present.
- Endemism – it is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type. Organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. A particular type of animal or plant may be endemic to a zone, a state or a country. The extreme opposite of endemism is cosmopolitan distribution.
- Among animals, insects are the most species-rich taxonomic group, making up more than 70 percent of the total. That means, out of every 10 animals on this planet, 7 are insects.
- The number of fungi species in the world is more than the combined total of the species of fishes, amphibians, reptiles, and mammals.
- Species diversity decreases as we move away from the equator towards the poles. With very few exceptions, tropics (latitudinal range of 23.5° N to 23.5° S) harbor more species than temperate or polar areas.
- Tropical Amazonian rain forest in South America has the greatest biodiversity on earth.
- o More than 40,000 species of plants
o More than 3,000 species of fishes
o More than 1,300 species of birds
o 427 of mammals
o 427 of amphibians
o 378 of reptiles
o More than 1,25,000 species invertebrates.
Communities with more species, generally, tend to be more stable than those with fewer species.
- Stable means not too much variation in productivity from year to year, resistant to occasional disturbances (natural or man-made) and also resistant to alien species invasion.
- Bioprospecting can be defined as the systematic search for and development of new sources of chemical compounds, genes, micro-organisms, micro-organisms, and other valuable products from nature. It entails the search for economically valuable genetic and biochemical resources from nature. So, in brief, bioprospecting means looking for ways to commercialize biodiversity.
- Nations endowed with rich biodiversity explore molecular, genetic and species-level diversity to derive products of economic importance.
- Keystone species, in ecology, a species that has a disproportionately large effect on the communities in which it occurs.
- Such species help to maintain local biodiversity within a community either by controlling populations of other species that would otherwise dominate the community or by providing critical resources for a wide range of species.
- These species are very important as an addition to or loss from an ecosystem leads to major changes in the occurrence of at least one other species.
- E.g. In an airplane (ecosystem) all parts are joined together using thousands of rivets (species). If every passenger traveling in it starts popping a rivet to take home (causing a species to become extinct), it may not affect flight safety (proper functioning of the ecosystem) initially, but as more and more rivets are removed, the plane becomes dangerously weak over a period of time. Furthermore, which rivet is removed may also be critical. Loss of rivets on the wings (key species that drive major ecosystem functions) is obviously a more serious threat to flight safety than the loss of a few rivets on the seats or windows inside the plane.
When a keystone species is removed from a habitat, the habitat is dramatically changed. All other species are affected and some may disappear from that ecosystem or even become extinct.
The population of deer or rabbits would explode without the presence of a predator. The ecosystem cannot support an unlimited number of animals, and the deer soon compete with each other for food and water resources. Their population usually declines without a predator such as a mountain lion.
Without the keystone species, new plants or animals could also come into the habitat and push out the native species. Some species of hummingbirds are keystone species in the Sonoran Desert of North America.
Ecosystem / Community Diversity
- It refers to different types of habitats.
o A habitat is the cumulative factor of the climate, vegetation, and geography of a region.
- The world consists of several types of habitat. E.g. Corals, grasslands, wetlands, desert, mangrove and tropical rain forests.
- 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 the biodiversity of species in the ecosystem is influenced by the nature of the ecosystem. E.g. species have more diversity in the Western Ghats than deserts of the Rajasthan.
Measurement of Biodiversity
Biodiversity is measured by 2 major components –
|o Species richness|
|o Species evenness|
It is the measure of a number of species found in a community (how rich they are?)
It is the diversity within a particular area or ecosystem.
It is expressed by the number of species (i.e. species richness) in that ecosystem.
It is a comparison of diversity between ecosystems.
It is measured as the change in the number of species between the ecosystems.
It is a measure of the overall diversity for the different ecosystems within a region.
It measures the proportion of species at a given site. E.g. low evenness indicates that a few species dominate the site.
Food web and its components are very important because tampering with them means disturbance in chain which leads to destruction of the species. Man is only a strand in the delicate web of relationship in the global ecosystem. Every time a species becomes extinct, the strand is broken and many species, including humans, move closer to extinction.
Services provided by Biodiversity
It provides a number of natural services for human beings
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
Medicinal resources and pharmaceutical drugs
Breeding stocks, population reservoirs
Diversity in genes, species, and ecosystems.
Research, education, and monitoring
Recreation and tourism
Causes for Biodiversity Loss
The accelerated rates of species extinctions that the world is facing now are largely due to human activities. There are four major causes (‘TheEvil Quartet’ is the sobriquet used to describe them).
Habitat loss and fragmentation
- o Most important cause.
o Tropical rainforests witnesses most dramatic examples of habitat loss. (Once covering more than 14% of the earth’s land surface, these rain forests now cover just 6%)
o The Amazon rain forest (They are so huge that they are called as ‘lungs of the
planet’) which are habitat of millions of species is being cut and cleared for
cultivating soya beans or for conversion to grasslands for raising beef cattle.
o Pollution also threatens the survival of many species. When large habitats are
broken up into small fragments due to various human activities, mammals and
birds requiring large territories and certain animals with migratory habits are badly affected, leading to population declines.
- o Human’s ‘need’ for food and shelter turns to ‘greed’ for profits.
o Many species extinctions in the last 500 years (Steller’s sea cow, passenger
pigeon) were due to overexploitation by humans.
o Over harvesting of marine fish populations endangered the continued existence of some commercially important species.
Alien species invasions
- o The introduction of exotic species is due to – horticulture, agriculture, European colonization, and accidental transport. Introduction of alien species
unintentionally or deliberately can cause decline or extinction of indigenous species.
o For example – introduction of Nile perch into Lake Victoria in east Africa led to the extinction of an ecologically unique assemblage of more than 200 species of
cichlid fish in the lake.
o Invasive weed species like carrot grass (Parthenium), Lantana and water
hyacinth (Eicchornia)can cause damage to environment and poses threat to
- o When a species becomes extinct, the plant and animal species associated with
it in an obligatory way also become extinct.
o For example –When a host fish species becomes extinct, its unique assemblage
of parasites also meets the same fate.
o Another example – coevolved plant-pollinator mutualism where extinction of
one invariably leads to the extinction of the other.
- o Since the animals are more vulnerable to infection, the anthropological activities
may increase the incidence of diseases in wild species, leading to their
Shifting or Jhum cultivation
- o The shifting or Jhum cultivation by poor tribal people greatly affects the forest
structure which is a storehouse of biodiversity.
- o Poaching, global warming, and other calamities.
In simple words it means conserving the biodiversity or saving the biodiversity.
Conservation of biodiversity is protection, upliftment and scientific management of biodiversity as to maintain it at its threshold level and derive sustainable benefits for the present and future generation.
In other words, conservation of biodiversity is the proper management of the
biosphere by human beings in such a way that it gives maximum benefits for the
present generation and also develops its potential so as to meet the needs of the future generations.
Biodiversity conservation leads to conservation of essential ecological diversity to preserve the continuity of food chains.
Conservation of biodiversity has many objectives –
- o To maintain essential ecological processes and life supporting systems.
o To preserve the genetic diversity of species.
o To make sustainable utilization of species and ecosystems.
o It provides a vast knowledge of potential use to the community.
Modes of conservation
When we conserve and protect the whole ecosystem, its biodiversity at all levels is protected – we save the entire forest to save the tiger. This approach is called in situ (on site) conservation.
However, when there are situations where an animal or plant is endangered or threatened and needs urgent measures to save it from extinction, ex-situ (off-site) conservation is the desirable approach.
Conserving biodiversity outside the areas where they naturally occur or in other words threatened animals and plants are taken out from their natural habitat and placed in a special setting where they can be protected and given special care.
Example – Zoological parks, botanical gardens, and wildlife safari parks.
In recent years ex-situ conservation has advanced beyond keeping threatened species in enclosures. Now gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques, eggs can be fertilized in vitro, and plants can be propagated using tissue culture methods. Seeds of different genetic strains of commercially important plants can be kept for long periods of in seed banks.
National gene bank of India –
- o It is primarily responsible for conservation of unique accessions on long-term
basis, as base collections for posterity, predominantly in the form of seeds.
Advantages of ex-situ conservation
It gives longer life time and breeding activity to animals.
Genetic techniques can be utilized in the process.
Captivity breed species can again be reintroduced in the wild.
The favourable conditions may not be maintained always.
Few life forms cannot evolve.
This technique involves only few species.
A zoo (short for zoological garden or zoological park, and also called an animal park or menagerie) is a facility in which animals are confined within enclosures, displayed to the public, and in which they may also breed.
Purpose of zoos – initially it was entertainment but over the decades, zoos have got transformed into centers for wildlife conservation and environmental education.
They play the role of saving individual animals and species conservation (through captive breeding).
They sensitizing visitors regarding the value and need for conservation of wildlife.
Botanical garden refers to the scientifically planned collection of living trees, shrubs, herbs,
climbers and other plants from various parts of the globe.
Purpose of botanical gardens –
To study the taxonomy as well as growth of plants.
To study the introduction and acclimatization process of exotic plants.
It acts as a germplasm (the genetic material of germ cells) collection.
It helps development of new hybrids.
It augments conserving rare and threatened species.
It facilitates training of staff.
It acts as a source of recreation.
A safari park is larger than a zoo and smaller than game reserves (large areas of land where wild animals live safely or are hunted in a controlled way for sport (in Africa)).
The conservation of species in their natural habitat or natural ecosystem is known as in-situ conservation.
In the process, the natural surrounding or ecosystem is protected and maintained so that all the constituent species (known or unknown) are conserved and benefited. suitable mechanism.
The established natural habitats are –
- o National parks
o Biosphere reserves
o Reserved forests
o Protected forests
o Nature reserves
The above natural habitat will be covered under chapter PROTECTED AREA NETWORK
If it is a cheap and convenient way of conserving biological diversity.
It offers a way to preserve a large number of organisms simultaneously, known or unknown to us.
The existence in natural ecosystem provides an opportunity to the living organisms to adjust to differing’ environmental conditions and to evolve into a better life form.
The only disadvantage – it requires a large space of earth which is often difficult because of the growing demand for space.