Lesson 7 of 8
Extinction
Goal: Explain why species become extinct.
A species is extinct when no individuals of it are left alive.
- A change in the environment can wipe out a species: a change in climate, a new predator, a new disease, a new competitor or the loss of its habitat.
- Humans cause many extinctions. Dodos lived on the island of Mauritius. Sailors hunted them, and the rats and pigs that came on the ships ate their eggs. Within about a hundred years, none were left.
- Variation protects a species. If its members differ, a few may have features that suit the new conditions. They survive and breed.
- Fossils show us species that died out long ago, such as Tyrannosaurus rex.
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Key words in this lesson
Variation The differences between living things
Species A group of living things that can breed together to produce fertile offspring
Extinct No individuals of the species are left alive