Lesson 3 of 6
Interdependence
Goal: Predict how a change in one population affects others.
The living things in a food web depend on each other, so a change in one population changes the others. This is interdependence.
- A population is all the living things of one species in an area, such as all the rabbits in a valley.
- More prey means more food for predators, so more predators survive. They then eat more prey, and the prey numbers fall.
- Disease, pollution and competition change populations too. Living things compete for food, water, light and space.
- A new, invasive species can upset a food web. Grey squirrels were brought to Britain from North America. They compete with red squirrels for food, and red squirrels have gone from most of England and Wales.
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Key words in this lesson
Food web Food chains from one ecosystem joined together
Predator An animal that hunts and eats other animals
Prey An animal that is hunted and eaten
Population All the living things of one species in an area
Interdependence Living things in a food web relying on each other
Competition A struggle for the same food, water, light or space