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Ecology has been derived from the Greek word ‘oikos’ meaning place of living. It is a branch of biology that studies how different organisms interact with one another and their surrenvironment. There are five levels of ecology namely- organism, population, community, ecosystem, and biosphere. These levels determines the hierarchy of organisms based on their sizes that eventually make the ecosystem.
What are the Five Levels of Ecology?
Five Levels of Ecology
Organism
One of the lowest levels of ecology is the organism level which consists of both unicellular and multicellular organisms. All living organisms present in this level exhibit all attributes necessary for survival. They can grow, reproduce, excrete, move, and respond to their surroundings. To put it simply, let us take an example-
- In water bodies (lakes, ponds, oceans), a single fish represent the first level of ecology that is organism.
- Living organisms reproduce via budding, fragmentation, sporulation, binary fission, meiosis, pollination, etc.
Population
The second level of ecology includes a group of organisms of the same species. In this stage, the organisms compete with each other for resources and the fittest survive as per Darwin’s theory of natural selection. When competition for food and water increases, there is a decrease in population growth leading to a decline in survival and reproduction rates of organisms.
- All fish living in the same area make a population.
- All the organisms present in a population grow, reproduce, and then die.
- Two organisms with similar needs for growth and reproduction compete with each other.
Community
The third level of ecology is the community where several populations interact in common surroundings and are dependent on one another. In a community, the interactions become more complex. According to community exclusion principle, it is very difficult for two species to live in a same habitat.
- Community ecology also called synecology is dependent on abiotic factors such as air, sunlight, temperature, etc.
- For instance, the interrelationship of organisms and their surrounding environment are represented by food chains and food webs.
- Another example is that, all populations like fish, sharks, and whales of different species in the surrounding form a community.
Ecosystem
The ecosystem deals with the interaction of both living and nonliving things. All biotic species like plants and animals interact with abiotic components like the soil, weather, air, sun etc. that are present in the surroundings. The ecosystem varies in size. A group of ecosystems where all the biotic and abiotic factors interact with one another and share common characteristics is called a biome.
- For instance, an ecosystem can be as big as a forest or as small as a pond.
- Ponds, puddles, trees, and rainforests are examples of an ecosystem.
Biosphere
The biosphere is the highest level of the ecosystem. It represents the vital part of the earth where life exists. There is an interaction with both biotic and abiotic components of the surroundings. A biosphere is composed of three major components: Lithosphere (outer layer of the earth), hydrosphere (all water bodies), and atmosphere (gaseous part of the earth). To maintain a global equilibrium, there is an interaction between the biosphere and its components (abiotic factors).
Things to Remember
- Ecology teaches us how environmental changes can affect organisms in an ecosystem.
- An example of a community is the collection of pine trees in a given area.
- One kind of interaction that occurs in the community is called competition.
- Abiotic and biotic factors are the two factors that affect ecology.
- The role of an organism in an ecosystem is called a niche.
Questions based on Ecology
Ques. What is a niche in ecology? Give an example. (2 marks)
Ans. Niche in ecology or ecological niche is defined as the role of a species in a community or ecosystem.
- Xerophytic plants are one of the several examples of an ecological niche.
- These plants can survive in dry conditions because they have thick leaves with water stored in them.
Ques. Explain any one type of ecology. (2 marks)
Ans. Molecular ecology is one of the seven types of ecology.
- Such a type of ecology deals with studying the production of proteins and how it affects the organism.
- Ecologists study the interactions between proteins and DNA and how the environment affects them.
Ques. What are the two ecological factors? (2 marks)
Ans. Abiotic and biotic components are the two factors of ecology.
- Water, sunlight, temperature, humidity, and air pressure are examples of abiotic factors.
- Plants, animals, birds, and bacteria, are examples of biotic factors.
Ques. What is the relevance of competition and predation in ecology? (2 marks)
Ans. Competition and predation are the two kinds of ecological factors.
- Competition is said to happen when organisms in a population compete for resources with one another.
- When one organism feeds on another to obtain food, this is called predation or predatory behavior.
Ques. In ecology, what are the other types of interactions? (2 marks)
Ans. The following are other ecological interactions in ecology:
- Commensalism
- Parasitism
- Mutualism
Ques. Give a few examples of ecological interactions. (2 marks)
Ans. The following are examples of ecological predators.
- Birds competing with each other for food is an example of competition.
- A wolf hunting a hare for its food is an example of predation
- Parasites living on the skin are an example of parasitism.
Ques. Is the biosphere the highest level of ecology? What do you know about the biosphere? (1 mark)
Ans. Yes, the highest level of ecology is the biosphere.
All life forms— air, water, land, living things, etc. are included in it.
Ques. Differentiate between a major and a minor community? (2 marks)
Ans. The difference between a major and a minor community is given below:
| Minor Community | Major Community |
|---|---|
| Small in size. | Large in size. |
| Less organized. | More organized. |
| Depend on other communities for survival. | Does not depend on other communities for survival. |
Ques. What is topography? Mention the 4 topographical factors. (2 marks)
Ans. Topography is the study of land surface and the factors which affect plants and animals in an ecosystem is called topographical factors. The 4 topographical factors are latitude, direction, altitude, and steepness of mountains. All these factors are related to the attributes of earth.
Ques. Differentiate between ecology and an ecosystem. (2 marks)
Ans. The difference between ecology and an ecosystem is given in the following table:
| Ecology | Ecosystem |
|---|---|
| Deals with the study of organisms and their interaction with the surroundings | It is a community of organisms that interact with each other and their surroundings |
| It is a branch of biology | It is a subgroup of the ecology |
| Ecology is of different types: human ecology, molecular ecology, organismal ecology, etc. | An ecosystem comprises forests, deserts, lakes, rivers, coral reefs, etc. |
Ques. Write a short note on human ecology. (3 marks)
Ans. Human ecology studies the effects of humans on the ecosystem.
It has been discovered that the increase in human activity harms the ecosystem resulting in climate change.
- Deforestation, burning of fossil fuels, and improper use of natural resources are how humans affect the biome.
- Human ecology also studies how humans and their behavior evolved, and what were the impacts of our environment on them.
Ques. What are edaphic factors in ecology? (2 marks)
Ans. Factors that are related to the physical, chemical, and biological properties of soil are the edaphic factors. Soil structure, texture, composition, pH, and fertility are examples of edaphic factors.
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