Table of Contents
- The term ecology was derived from two Greek words ‘Oikos’ meaning home and ‘logos’ meaning study.
- Ecology is the branch of biology concerned with the relations of organisms to one another (energy flow and mineral cycling) and to their physical surroundings
- Environment is the natural component in which biotic (living) and abiotic (non-living) factors interact among themselves and with each other.
- These interactions shape the habitat and ecosystem of an organism.
Levels of Organisation
- Ecology encompasses the study of individual, organisms, population, community, ecosystem, biome and biosphere which form the various levels of ecological organisation.
- Individual and Species
- Organism is an individual living being that has the ability to act or function independently.
- Species are a group of living organisms consisting of similar individuals capable of exchanging genes or of interbreeding.
Population
- Population is a community of interbreeding organisms (same species), occupying a defined area during a specific time.
- Population growth rate can be positive due to birth and/or immigration or negative due to death and/or emigration.
Community
- Communities in most instances are named after the dominant plant form.
- For example, a grassland community is dominated by grasses, though it may contain herbs, trees, etc.
Ecosystem
- An ecosystem is a community of organisms interacting with each other and with their environment such that energy is exchanged and system-level processes, such as the cycling of elements, emerge.
Biome
- A biome is a large naturally occurring community of flora and fauna occupying a major habitat. E.g. Rainforest biome or tundra biome.
- Plants and animals in a biome have common characteristics due to similar climates and can be found over a range of continents.
Biosphere
- The biosphere includes all living organisms on earth, together with the dead organic matter produced by them.
Biosphere
- The biosphere is the biological component (supporting life) of the earth which includes the lithosphere, hydrosphere and atmosphere.
- The biosphere includes all living organisms on earth, together with the dead organic matter produced by them.
- Habitat
- Habitat is the physical environment in which an organism lives (address of an organism).
- Many habitats make up the environment.
- A single habitat may be common for more than one organism which have similar requirements.
Ecosystem
- An ecosystem can be visualised as a functional unit of nature, where living organisms (producers, consumers, and decomposers) interact among themselves and also with the surrounding physical environment.
- An ecosystem can be of any size but usually encompasses specific and limited species. E.g. Aquatic Ecosystem.
Classification of Ecosystems
- Forest, grassland and desert are some examples of terrestrial ecosystems; pond, lake, wetland, river and estuary are some examples of aquatic ecosystems.
- Crop fields and an aquarium are human-made ecosystems.
Adaptation
- An adaptation is, “the appearance or behaviour or structure or mode of life of an organism that allows it to survive in a particular environment”.
- Adaptation may be:
- Morphological – when trees grew higher, the giraffe’s neck got longer;
- Physiological – in the absence of an external source of water, the kangaroo rat in North American deserts is capable of meeting all its water requirements through its internal fat oxidation
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Variation
- Variations are induced by changes in genetic makeup due to addition or deletion of certain genes.
- Mutations, change in climate, geographical barriers etc. induce variations over a period of time.
Adaptive radiation
- Adaptive radiation is a process in which organisms diversify from an ancestral species into a multitude of new forms when the environment creates new challenges or opens new environmental niches.
Speciation
- Speciation is the process by which new species are formed, and evolution is the mechanism by which speciation is brought about.
- A species comprises of many populations. Often different populations of a species remain isolated due to some geographic barrier such as mountain, ocean, river, etc.
Mutation
- Mutation (a change in genetic material that results from an error in replication of DNA) causes new genes to arise in a population.
Natural Selection
- Natural Selection is the mechanism proposed by Darwin and Wallace.
- Natural selection is the process by which species adapt to their environment.
- It is an evolutionary force that selects among variations, i.e. genes that help the organism to better adapt to its environment. Such genes are reproduced more in a population due to natural selection.
Evolution
- Evolution is the change which gives rise to new species.
- It happens in order to make the organism better suitable to the present environment.
Extinction
- The primary reason behind extinctions is environmental change or biological competition.
- Extinction occurs when species cannot evolve fast enough to cope with the changing environment.
- At present, the 6th Mass Extinction (Anthropogenic Extinction – human induced) is in progress.
Components of an Ecosystem
- The components of the ecosystem are categorized into abiotic or non-living and biotic or living components. Both the components of the ecosystem and environment are the same.
Abiotic Components
- Abiotic components are the inorganic and non-living parts which act as major limiting factors.
- Biotic Components
Types of Ecology
- Q. Which one of the following is the best description of the term “ecosystem”?
- 1.A community of organisms interacting with one another
- 2.That part of the Earth which is inhabited by living organisms
- 3.A community of organisms together with the environment in which they live.
- 4.The flora and fauna of a geographical area.
Important Terms of Ecology and Environment | Free PDF
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