Natural Selection and Evolution

Objectives

• Students will be able to-– Explain the theory of natural selection– Apply the theory of natural selection to

hypothetical situations.– Identify frog and amphibian similarities to other

species.

Did you see any animal variation at the Zoo? Why do you think there was so

much of it?

Did you see any animal variation at the Zoo? Why do you think there was so

much of it?

Animals are suited to their environment.

What do you know about the following terms?

• Natural Selection-

• Adaptation-

• Population-

Population

• Population- Individuals species that live together in one place at one time and can interbreed.

Natural Selection

• The process by which individuals that have favorable variations, and are better adapted to their environment, survive and reproduce more successfully than less well adapted individuals.

Adaptation

• An inherited trait that has become common in population because the trait has provided a selective advantage.

Question/Example

• In a natural frog population, the skin color varies from red to blue to green. None of the frogs are poisonous, but there are a lot of predators in the area. The surrounding are is covered with green plants. Who is most likely to survive?

Question/Example

• In a natural frog population, the skin color varies from red to blue to green. None of the frogs are poisonous, but there are a lot of predators in the area. The surrounding are is covered with green plants. Who is most likely to survive?

Question

• If natural selection is the reason behind successful adaptations, why don’t beavers have chainsaws?

Question

• If natural selection is the reason behind successful adaptations, why don’t beavers have chainsaws?

Genetic Variation

• There has to be variation that can be inherited in order for Natural selection to take place.

• If a population happens to have the genetic variation that allows some individuals to survive a particular challenge better than

others, then those individuals will have more offspring in the next generation