1. Natural Selection

2. Charles Darwin (1809-1882) Studied biology
In 1831 at age 22, he accepted a job on the HMS Beagle as a scientist
The HMS Beagle docked at the Galapagos Islands off the coast of South America

3. Charles Darwin ( )
Based on fossil evidence, Darwin knew plants and animals change over time
Believed organisms had changed slowly over time and would keep changing
The environment and adaptability of the organisms controlled the changed.

4. What he saw in the Galapagos…

5. What he saw in the Galapagos…
Each island had similar animals with slightly different traits
Long or short necked tortoises depending on the plant height

6. What he saw in the Galapagos…
Finches had many different beak sizes and shapes depending on diet

7. Natural Selection
Darwin’s theory that organisms changed over time based on traits that helped them survive
Survival of the fittest

8. Natural Selection
Organisms with traits that help them survive grow and reproduce passing on those traits to their offspring
Organisms with traits that don’t help them survive are usually eaten or die and don’t pass on their traits

9. Natural Selection
Factors that can affect the process of natural selection
Overproduction of offspring in a species
Competition among organisms of same species
Genetic variations within a population

10. Peppered Moths In England there is a species of peppered moth
They come in two color variations
Light
dark
The trees they lived on had a light bark color
During the industrial revolution, factories were built that produced soot
The soot stained the tree bark black

11. Peppered Moths light dark
Use the moth and bark pictures on your desk to answer.
Which moths were better adapted to the trees before pollution?
Which moths were adapted to the trees after the pollution?
light
dark

12. Elephant Example
Let’s say a group of elephants had mostly short trunks
But a few of the elephants in the group had slightly longer trunks than others
When food and water became scarce, the elephants with longer trunks could reach higher for food and deeper into holes for water

13. Elephant Example
Elephants with shorter trunks would die of thirst and starvation
Elephants with longer trunks would survive and reproduce passing on their longer trunks
Over time, the group would consist mostly of long trunked elephants

15. Elephant Example
Put the elephant cards in the right order