Natural Selection

Charles Darwin’s

In 1831, Charles Darwin began a 5 year trip around the world aboard

the H.M.S. Beagle.

His goal was to observe and study new species of plants and animals.

One of the stops was the Galapagos Islands. The ship spent 5 weeks there.

Darwin observed many new species on the islands.

He also noticed how there were many similarities, and differences, between the species living on the islands and the

mainland.

Darwin concluded that, over time, species must change based on their survival needs, to become better adapted.

Over the next 20 years, Darwin consulted with other scientists

and gathered more information.

In 1858, Darwin published his theory of natural selection.

Natural Selection

Individuals that are better adapted to their environment are more likely to survive and reproduce more than the other members of the same species.

Natural selection depends on 4 factors:

1. Overproduction

Species produce far more offspring than can possibly survive.

2. Variation

Members of a species differ from one another.

3. Competition

Members of a species must compete with one another for limited resources (food, water, space, etc.)

4. Selection

Some members are better adapted. They will survive, reproduce, and pass their favorable

variations (adaptations) on to their offspring.

Eventually, the majority of the members of the species will have those favorable traits and

most of the unfavorable traits will disappear.

This is why natural selection is nicknamed “Survival of the Fittest”.