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Extinction occurs when there are no remaining individuals of a species left alive. Animals that have not adapted well to their environment are less likely to survive and reproduce than those that are well adapted. The animals that have not adapted to their environment may become extinct.

Extinction has a role in evolution as some species disappear, whilst others survive and continue to evolve. Several factors can cause a species to become extinct. They include:

• new diseases
• new predators
• new, more successful competitors
• changes to the environment over geological time, such as climate change
• a single catastrophic event, such as a massive volcanic eruption, or a collision between an asteroid and the Earth

A species may also become extinct through speciation.

The fossil record shows that many species have become extinct since life on Earth began. Extinction is still happening, and it is often due to human activities. Humans compete with other living organisms for space, food and water – humans are very successful predators.

The dodo

Dodos lived on the island of Mauritius in the Indian Ocean. The island was uninhabited and the birds had no natural predators. When Mauritius was colonised by the Dutch in 1638, dodos were hunted for food. They were easy to catch, and new competitors were brought onto the island, such as pigs, cats and rats. They ate the dodos’ eggs and their young. Within 80 years, the dodo was extinct.