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  1. Ecological concepts
  2. Components of an ecosystem
  3. Local biotic communities or biomes


Ecology is the study of living organisms in relation to their environment.

The study deals with the relationship of living organisms with one another and with the environment in which they live. Ecology measures factors affecting the environment; it studies the distribution of living organisms and how they depend on one another and their non-living environment for their survival.

Ecology is divided into two

(i) Autecology which is the study of a single individual organism or a single species of organism and their environment. E.g. the study of Tilapia fish in a particular stream.

(ii) Synecology which is the study of inter–relationships between groups of organisms or species of organisms living together in an area. E.g. the study of all organisms in a particular stream in relation to their environment.

Ecology Concepts

Environment: This refers to all the factors in an organism’s surroundings, living or non-living. The factors include the place where the organism lives and the physical conditions in the place, the food, water and air it takes in, the animals that prey on it and the disease that affect it.

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Habitat: This is the place where an organism lives. It is the place that is suitable to the organism’s way of life e.g. the habitat of fish is water.

Examples of habitats include:

  • Aquatic habitats e.g. puddles, streams, ponds, seas, oceans.
  • Terrestrial habitats e.g. savanna, rain, forest, desert, etc.
  • Arboreal habitat i.e. tree tops and tree trunks.
  1. Ecological Niche: This is the functional role and the space / specific portion of habitat occupied by a particular organism or species. E.g. a caterpillar and an aphid may live on the same plant but occupy different positions. The caterpillar lives on the leaves and feeds on them while the aphid lives on the young shoot / stem and sucks sap from it. The functional role includes the organism’s behaviour, its feeding habits and breeding habits i.e. the activities carried out while occupying the spaces in the habitat.
  2. Population: This is the total number of all organisms of the same species or kinds, living together in a given area / habitat. E.g. the total number of Tilapia fish in a pond constitutes the population of Tilapia fish in that habitat.
  3. Community: This is made up of all the populations of living organisms that exist together in a habitat. It is any natural occurring group of different organisms living together and interacting in the same habitat. E.g. the community on a rotting log will include insects like termites, ants, lizards, small birds and decomposers such as bacteria and fungi.
  4. Biosphere: This refers to all parts of the atmosphere, hydrosphere and lithosphere where life can be found. It is the largest and highest level of biological organization and is made up of various ecosystems.
  5. Ecosystem: This is self – supporting unit that is made up of a living part and a non-living part. It is a community of plants and animals interacting with themselves and with the non-living factors in their environment.
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