Evolution and Ecological Biodiversity
Category : UPSC
EVOLUTION AND ECOLOGICAL BIODIVERSITY
EVOLUTION
The branch of life science for the study of ‘origin of life’ and evolution of different forms of life on earth was called bio evolution or evolutionary biology by Mayer, (1970). The word evolution means to unfold or unroll or to reveal hidden potentialities. Evolution simply means an orderly change from one condition to another. Evolution is slow but continuous process which never stop.
ORIGIN OF LIFE
Chemosynthetic Theory of Origin of Life
The widely accepted theory is the Chemosynthetic theory of origin of life proposed by A.I. Oparin. It states that life has originated on earth through a series of combinations of chemical substances in the distant past. All these processes took place in water.
(\[C{{H}_{4}}\]). At that time there was no free oxygen.
Miller and Urey Experiment
CHEMICAL EVOLUTION AND ORGANIC EVOLUTION
Comparative Anatomy and Morphology
Let us discuss some of the important sources that provide evidences/or evolution.
For example, the forelimbs of humans and the wings of birds look different externally but their skeletal structure is similar.
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For example, the wings of a bird and a bat are similar in function but this similarity does not mean that these animals are more closely related.
Vestigial organs
Theories of Organic Evolution
(i) Lamarckism
(ii) Darwinisms
(iii) Mutation theory
(iv) Modern concept of evolution (synthetic theory)
Lamarckism
Long neck and high fore limb of Giraffe, Aquatic birds stretched their toes and developed web, Snakes lost their legs, Deers became good runners by the development of strong limbs and streamlined body and retractile claws of carnivorous animals.
Darwinism
(i) “Principles of Population” by Malthus.
(ii) “Principles of Geology” by Charls Lyell.
Main features of theory of Natural Selection
- All organisms have capability to produce enormous number of offspring, organisms multiply in geometric ratio.
- E.g.
(i) Plants produce thousands of seeds.
(ii) Insects lay hundreds of egg.
(iii) One pair of elephant gives rise to about six offspring and if all survived in 750 years a single pair would produce about 19 million elephants. Thus, some organisms produce more offspring and other produce fewer offspring. This is called differential reproduction.
Mutation Theory
(i) It forms the raw material for mutation.
(ii) It appears suddenly and produce their effect immediately.
(iii) Mutations are markedly different from the parents and there are no intermediate stages between the two.
(iv) Mutations can appear in all directions.
HUMAN EVOLUTION
Evolution of man probably took place in Central Africa. Human evolution states that human develops from primates or ape like ancestors. Anthropology is the study of human evolution and culture. It deals with the fossils of pre-historic and living man. Homo erectus was the first human to leave Africa and move to Europe and Asia. It had a sloping forehead, flattish face and brain size between 850-1100 ml. These humans exploited more habitats than their ancestors. They were first to use fire.
Homo nenderthals were the first humans to have adopted to life in cold climates of Europe and Asia. They had strong physique and large brain. They more clothes, made a range of tools and used fire to keep warm. They were the first humans to bury their dead.
Homo sapiens or the “modem human” first evolved in Africa. They had a large brain, were considerably intelligent and had developed the ability to use language. Modem man took control of their surroundings as they developed agriculture, societies and technology.
Handy Facts
ECOLOGY AND BIODIVERSITY
The term “ecology” was coined in 1866 by German scientist Ernst Hackel. It is study of biota, environment and their interaction. Ecology also provides information about the benefits of ecosystems and how we can use Earth's resources in ways that leave the environment healthy for future generations. Ecology can studied in following head.
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Ecology |
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Population ecology |
Community ecology |
Ecosystem ecology |
Behavioural ecology |
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This is also known as autecology. It is a part of ecology that deals with the variety of species population and their interaction with their environment. It is the study of size of population of species changing over time and space. |
This is also known as Bio coenosis. It is the assemblage of two or more different species that occupies same geographical area. |
It is a part of ecology that studies biotic and abiotic components of ecosystem and their interaction of the ecosystem. |
It is a part of ecology that deals with the ecological, environment?s developmental, genetic and social influences of species and their responses to the stimuli. It shows the way of such responses that affects the fitness of organism. |
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ECOSYSTEM
Components of Ecosystem
Structure and Function of Ecosystem
Decomposition
Process of Decomposition
(i) Fragmentation
It is the formation of smaller pieces of dead organic matter or detritus by detritivores. Due to fragmentation, the surface area of detritus particles is greatly increased.
(ii) Catabolism
Chemical conversion of detritus into simpler inorganic substances with the help of bacterial and fungal enzymes is called catabolism.
(iii) Leaching
Water soluble substances (formed as a result of decomposition) are leached to deeper layers of soil.
(iv) Humification
If decomposition leads to the formation of colloidal organic matter (humus), the process is called humification. Humus is highly resistant to microbial action and undergoes extremely slow decomposition. It serves as a reservoir of nutrients.
(v) Mineralisation
Formation of simpler inorganic substances (like \[C{{O}_{2}},\] water and minerals) is termed mineralisation.
FOOD CHAIN
Types of food chains
The food chains are of two types, namely:
(i) Grazing food chain: This food chain starts from plants, goes through herbivores and ends in carnivores, ex- Plant \[\to \] Herbivores \[\to \] Primary Carnivores \[\to \] Sec. Carnivores. This type of food chain depends on the autotrophs which capture the energy from solar radiation.
(ii) Detritus food chain: It starts from dead organic matter and ends in inorganic compounds. There are certain groups of organisms which feed exclusively on the dead bodies of animals and plants. These organisms are called detritivores. The detritivores include algae, bacteria, fungi, protozoans, insects, millipedes, centipedes, crustaceans, mussels, clams, annelid worms, nematodes, ducks, etc.
FOOD WEB
Example: In a grassland ecosystem
ECOLOGICAL PYRAMIDS
ECOLOGICAL SUCCESSION
Types of Succession
Hydrach/Hydrosere Succession
Xerarch Succession
Crustose lichens \[\to \] foliose lichens \[\to \] mosses \[\to \] grasses \[\to \] shrubs \[\to \] trees.
NUTRIENT CYCLING
(i) Gaseous cycles (nitrogen, oxygen, carbon cycles)
(ii) Sedimentary cycles (phosphorus, sulphur cycles)
Carbon Cycle
(i) respiration of plants and animals
(ii) burning of fossil fuels
Phosphorus Cycle
NITROGEN CYCLE
Broadly, the nitrogen cycle in the biosphere involves five main steps:
Atmospheric nitrogen \[\to \] Nitrogen fixation \[\to \] Nitrogen assimilation\[\to \] Ammonification \[\to \] Nitrification \[\to \] Denitrification
(i) Nitrogen fixation: It is the process of converting atmospheric nitrogen into usable forms like nitrates. It is of three types:
(ii) Nitrogen assimilation: Nitrogen assimilation is carried out by plants. Plants cannot absorb nitrogen in its elemental form. It has to be first converted into nitrates for the use of plants by the process of nitrogen fixation. The atmospheric nitrogen after nitrogen fixation gets converted into nitrates which are then absorbed by plants. Nitrate first changes into ammonium state. Ammonium ions combine with organic acids to form amino acids. Amino acids give rise to proteins and nucleotides, which in turn produce nucleic acids.
Animals take organic nitrogen directly or indirectly from plants.
(iii) Ammonification: It is the process of conversion of complex organic compounds like proteins into ammonia, in the presence of ammonifying bacteria or putrefying bacteria.
(iv) Nitrification: It is the process of conversion of ammonia into nitrites and nitrates. Nitrification is brought about by nitrifying bacteria such as Nitrosomonas and Nitrobacter.
(v) Denitrification: It is the process of conversion of nitrate salts present in the soil and water to gaseous nitrogen which escapes into atmosphere. It takes place with the help of bacteria called Pseudomonas present in water logged soils. Denitrification reduces soil fertility.
Water Cycle (Also known as hydrological cycle)
Water cycle is the cyclic process of water between various components of biosphere especially evaporation of water from sea, falling on land and then flowing back into sea by rivers. Water is not evenly distributed throughout the surface of the earth. Major percentage of the total water on the earth is chemically bound to rocks and does not cycle. Out of the remaining, nearly 97.3% is in the oceans and 2.1% exists as polar ice caps. Thus only 0.6% is present as fresh water (in the form of atmospheric water vapors, ground and soil water). The ice caps and the water deep in the oceans form the reservoir.
Sulphur Cycle
BIODIVERSITY
Biodiversity means diversity or heterogeneity at all levels of biological organization, i.e., from macromolecules of the cells to the Biomass. The term Biodiversity was popularized by the sociologist- Edward Wilson.
Genetic Diversity
Species Diversity
The measurement of species diversity is its richness, i.e. the number of species per unit area. The greater is the species richness the more will be the species diversity.
Ecological Diversity
It is the diversity at community level. It can be of 3-types
Alpha (\[\alpha \]) diversity
It is the diversity of organisms within the same community or habitat.
Beta (\[\beta \]) diversity
It is the diversity between communities or different habitats. Higher the heterogenecity in the altitude, Humidity and Temperature of a region, the greater will be the dissimilarity between communities, and higher will be the P diversity.
Gamma (\[\gamma \]) diversity
It is the diversity of organisms over the entire geographical area, covering several ecosystems or habitats and various trophic levels and food webs. Such diversity is most stable and productive.
Loss of Biodiversity
Causes of Loss of Biodiversity
The accelerated rate of species-extinction is largely due to human activities. There are 4-major causes, called ‘The Evil Quartet’, for the loss of biodiversity are: Habitat loss and fragmentation, Overexploitation, Invasion of Alien or exotic species and Co-extinctions
Habitat loss and fragmentation
Overexploitation
Invasion of Alien or exotic species
When alien species are introduced into an explored area, some of the species turn invasive and cause decline or extinction of indigenous species. For example -
Co-extinctions
CONSERVATION OF BIODIVERSITY
Conservation means management of human-use of the biosphere so that it may yield greatest long term (sustainable) benefits for the present generation by maintaining its potential to meet the needs and aspiration of future generations. The Conservation of biodiversity can be in situ (on site) or exsitu (offsite)-
In Situ Conservation
Biosphere reserves
They represent natural biomes which contain unique biological communities. They include land as well as coastal environment. Biosphere reserves were created under MAB (Man and Biosphere) programme of UNESCO in 1971. Till May 2000 there were 408 biosphere reserves in 94 countries of the world. In India there are 15 biosphere reserves. There are 3-zones in a biosphere reserve.
Functions of biosphere reserves
The list of biosphere reserves of India is given below:
National Parks
They are reserved for the betterment of wild life, booth fauna and flora. In national parks private ownership is not allowed. The grazing, cultivation, forestry etc. is also not permitted. The first national park of the world. Yellow stone, in U.S.A., was founded in 1872.
Important state wise national parks of India are –
Jammu and Kashmir |
Dachigam, Salim Ali |
Assam |
Kaziranga, Manas |
Meghalaya |
Nokrek |
West Bengal |
Sunderbans |
Bihar |
Hazaribagh, Palamau |
Uttaranchal |
Corbett ( Hailey ), Nanda Devi, Valley of flowers, Rajaji |
U.P. |
Dudhwa |
Gujarat |
Gir, Marine |
Rajasthan |
Sariska, Ranthambore, Desert |
Madhya Pradesh |
Kanha, Sanjay, Madhav, Panna, Bandhavgarh, Van Vihar, Fossil |
Orissa |
Simlipal |
Karnataka |
Bandipur |
Kerala |
Silent Valley, Periyar |
These national parks are running Tiger Project also. (The maximum national parks are present in Madhya Pradesh).
Sanctuaries
In sanctuaries the protection is given to fauna only. The important wild life sanctuaries are Chilka wild life sanctuary (Orissa), Bharatpur Bird Sanctuary (Rajasthan), Sultanpur Bird sanctuary (Haryana) and Jalpara sanctuary (West Bengal). Maximum sanctuaries belong to Andaman and Nicobar.
The Project Tiger was launched in India in year 1973 with the assistance of WWF (World Wild life Fund) after the recommendation of IBWL (Indian Board of Wild Life).
The sacred groves are found in Khasi and Jaintia hills (Meghalaya), Aravalli hills (Rajasthan), Western ghats (Karnataka and Maharashtra) and Sarguja, Chanda and Bastar areas of Madhya Pradesh.
Ex situ Conservation
In such type of conservation the threatened animals and plants are taken out of their natural habitat and are protected in special parks or areas like, Zoological parks, Wild life safari parks and Botanical gardens etc. The ex situ conservation also includes
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