ATS COACHING CLASSES
REVISION NOTES
BIODIVERSITY AND CONSERVATION
Earth has an enormous diversity of life that we encounter, for humans the rich variety of living organism never ceases to astonish and fascinate them, there are more than 20,000 species of ant, 3,00,000 species of beetles, 28,000 species of fishes and nearly 20,000 species of orchids on a planet.
Biodiversity: The occurrence of different types of ecosystems, different species of organisms, and their variants such as biotypes, ecotypes, and genes adapted to different climates and environments of different regions, as well as their interactions and processes, is referred to as biodiversity or biological diversity.
Edward Wilson was the first person to use this term.
Various microorganisms like algae, fungi, plants, and animals found on Earth, whether in terrestrial or aquatic places and ecological systems of which they are a part, is referred to as biodiversity. Different types of biodiversity’s are:
(i) Genetic biodiversity: a single species may show high level of diversity at the genetic level over its distributional range. E.g. Rauwolfia serpentine, rice ( more than 50,000 stains) and mango (1000 different varieties.)
(ii) Species diversity: diversity at species level. E.g. number of amphibian species in the Western Ghats are more than the Eastern Ghats.
(iii) Ecological diversity: individual ecosystems have great level of biodiversity within them. Examples of ecological diversity are deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, alpine meadows etc.
One of the most important environmental concerns of worldwide significance is biodiversity and how we can conserve it. The concern is growing day by day as more people throughout the world recognise the fundamental relevance of biodiversity for the sustainment of life and well-being on this planet.
Some extreme estimates range from 20 to 50 million, but a more conservative and scientifically sound estimate made by Robert May places the global species diversity at about 7 million. According to the IUCN, the total number of plant and animal species described thus far is around 1.5 million, although many species have yet to be discovered and described.
Animals constitute 70% species of the world, with the remainder being planted such as algae, fungi, bryophytes, gymnosperms, and angiosperms and insects account for 70% of all animals. Fungal species on earth exceed the number of fish, amphibians, reptiles, and mammals combined.
Representation of global diversity: proportionate number of species of major taxa of plants, invertebrates and vertebrates
Biodiversity of India
One of the twelve Mega diversities countries of the world is India which has only 2.4 % of the land area of the world, it has 8.1 % of global species biodiversity, research has shown that there are about 45,000 species of plants and 90,000 to 1 lakh species of animals that are yet to be discovered till now. As per Robert May, 22% of the total species have been recorded. 1,00,000 plant species and 3,0,0000 animal species are yet to be discovered.
Patterns of Biodiversity
•Longitudinal Gradients: The variety of plants and animals is not consistent throughout the earth and is distributed unevenly. In terms of diversity, this distribution pattern follows the latitudinal gradient. As we travel farther from the equator and toward the poles, the variety of species declines. Tropics are home to more species than temperate or polar regions. The Amazonian Rainforest hosts the most biodiversity on the planet. It includes about 40,000 plant species, 1,25,000 insect species, 300 fish species, 427 amphibian and 378 reptile species, 1300 bird species, and 427 mammals. Why is that so? Let’s have a look at some hypotheses:
o Speciation: it is generally a function of time like temperate regions subjected to frequent glaciations in the past tropical latitudes have remained relatively undisturbed from millions of years and the had a long evolutionary time for species diversification.
o Tropical environment: unlike temperate ones are less seasonal relatively more constant and predictable such constant environment promotes niche specialization and lead to a better species diversity.
o Solar energy: solar energy in the Tropic contributes to higher productivity that contribute to Greater diversity.
o Species area Relationship: German naturalist and geographer Alexander Von Humboldt while his excavations in the South American jungles found that species richness increases with increasing explored area but only up to a certain limit, the relationship between species richness and area for a wide variety of taxa is a rectangular hyperbola while on a logarithmic scale the relationship is a straight line and is represented by the equation:
Log S = log C + Z log A
Where: S: species richness
A: area Z: slope of the line (regression coefficient)
C: Y-intercept
Graph showing species area relationship The value of Z lies in the range of 0.1 to 0.2 regardless of the taxonomic group of the region, for continents the value of Z is 0.6 to 1.2. For frugivorous (fruit-eating) birds and mammals in the tropical forests of different continents, the slope is found to be 1.15.
Importance of Species Diversity to the Ecosystem
A community with more species is more stable. A stable community should not show too much variation in productivity from year to year; it must be either resistant or resilient to occasional disturbances (natural or man-made), and it must also be resistant to invasions by alien species. Tilman found that plots with more species showed less year to-year variation in total biomass. He also showed that in his experiments, increased diversity contributed to higher productivity.
Loss in Biodiversity: Our planets' biological richness is fast dwindling owing to three factors:
▪ Population
▪ Urbanization, and
▪ Industrialization.
The IUCN Red List (2004) records the extinction of 784 species in the previous 500 years (containing 338 vertebrates, 359 invertebrates, and 87 plants). Extinct species include the dodo (Mauritius),Quagga (Africa), thylacine (Australia), Steller's Sea Cow (Russia), and three tiger subspecies (Bali, Javan, and Caspian). 27 species have become extinct in the previous 20 years. If a region continuously loses its biodiversity then it may cause:
✓ Less plant production.
✓ Impact of environmental protuberances like drought and flood will be more.
✓ Increased variability in certain ecosystem processes like plant productivity, water use and pest and disease cycles.
Causes of loss in Biodiversity: loss in Biodiversity occurs due to:
(i) Habitat loss and fragmentation: it is the leading cause of animal and plant extinction. Our planet’s lungs that is the Amazon rain forest which contains millions of species, is being chopped and cleared for soya bean cultivation or conversion to grasslands. When broad ecosystems are fragmented into small bits as a result of numerous human activities, animals and birds that require large territories move and are negatively impacted.
(ii) Over-exploitation: Man's overexploitation of biological systems for natural resources results in deterioration and extinction of resources, such as Steller's sea cows and passenger pigeons. Many marine fish populations are overfished, threatening the survival of certain key species.
(iii) Invasion of alien species: When alien species enter the environment, whether purposefully or inadvertently, some of them become invasive and cause the decrease or extinction of indigenous species. The introduction of Nile perch into Lake Victoria in east Africa finally led to the demise of an ecologically unique assemblage of over 200 species of cichlid fish in the lake. Invasive weeds such as carrot grass (parthenium), Lantana, and water hyacinth pose a danger to native species.
(iv) Co-extinctions: When a species becomes extinct, the plant and animal species that are dependent on it also vanish.
Conservation of Biodiversity
We should conserve biodiversity because:
(i) Narrow utilitarian: Nature provides humans with several direct economic advantages such as food, fuel, fibres, building materials, medicinal plants, and industrial goods. Nations endowed with high biodiversity should expect to gain significant benefits as resources are poured into 'bio-prospecting’ (exploring molecular, genetic and species level diversity for products of economic importance).
(ii) Broadly utilitarian: argument says that biodiversity plays a major role in many ecosystem services that nature provides. Biodiversity is important in the ecological services that nature delivers. Oxygen production during photosynthesis, pollination without a natural pollinator, and enjoyment from nature are all priceless.
(iii) Ethical: Conservation of biodiversity refers to what we possess in relation to the millions of plant, animal, and microbial species with whom we share our world. Every species has intrinsic worth, even if it has little immediate or economic benefit to humans. It is our moral obligation to look for their well-being and to leave our biological heritage in excellent condition for future generations.
How can we conserve our Biodiversity?
We can conserve our biodiversity in two ways:
(i) In-situ conservation: when we conserve and protect the whole ecosystem, its biodiversity at all levels is protected, for example, we save the entire forest so as to save the tiger, this approach is called in-situ or onsite conservation. There are 34 biodiversity hot spots in the world. These hotspots are also regions of accelerated habitat loss. These hotspots are also regions of accelerated habitat loss. Three of these hotspots – Western Ghats and Sri Lanka, Indo-Burma and Himalaya – cover our country’s exceptionally high biodiversity regions. Although all the biodiversity hotspots put together cover less than 2 per cent of the earth’s land area, the number of species they collectively harbour is extremely high and strict protection of these hotspots could reduce the ongoing mass extinctions by almost 30 per cent. India has 14 biosphere reserves, 90 national parks and 448 wildlife sanctuaries. India has also a history of religious and cultural traditions that emphasised protection of nature. In many cultures, tracts of forest were set aside, and all the trees and wildlife within were venerated and given total protection. Such sacred groves are found in Khasi and Jaintia Hills in Meghalaya, Aravalli Hills of Rajasthan, Western Ghat regions of Karnataka and Maharashtra and the Sarguja, Chanda and Bastar areas of Madhya Pradesh. In Meghalaya, the sacred groves are the last refuges for a large number of rare and threatened plants.
(ii) Ex-situ conservation: however, there are situations where an animal or plant is endangered or threatened and need urgent measures to save it from extinction, this approach is called ex-situ or off-site conservation. In such cases, threatened animals and plants are kept in zoological parks, and botanical gardens. 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 in seed banks.