1. Theory of Evolution by Natural Selection
Strand 5: Changes in Species over Time
7.5.1 Developing Traits that Affect Survival
Theory of Evolution by Natural Selection
Charles Darwin

2. Darwin wondered… Why are organisms different?
Why are organisms similar?
Why are there so many different types of organisms?

3. 1831—Darwin set sail on the Beagle to make maps of the coast of South Africa

4. During his 5 year exploration voyage, he did geological studies of the areas to find minerals for mining, and he was free to study the plants and animals of each area. He took detailed notes and made lots of drawings.

5. Darwin was very interested in the organisms he examined on the Galapagos Islands

6. Many animals and plants were unique to each island.
There were birds called finches that had its own habits and ate its own kind of food, but appeared to be closely related.

7. The finches came from a common ancestor
The finches came from a common ancestor. They evolved as they adapted to different food that was available to them on different islands.

8. The shapes of the finch beaks were well-matched with the seeds available on the island where it lived. Larger and stronger beaks were needed to break open large seeds available on one island and small, pointed beaks were needed to efficiently eat the cactus fruits and flowers from another island.

9. Each island had a different type of tortoise and it is possible to identify a tortoises home island from the shape of its shell.

10. The Principle of Natural Selection
An organism that has traits (genes) that are best suited to survive changes in the environment is the one that will live longest and healthiest and reproduce offspring with those same genes.

11. Natural Selection will occur when:
There is some variation in the inherited traits of organisms within a species.
Some of these traits will give individuals an advantage over others in surviving and reproducing
These individuals will be likely to have more offspring and pass on the beneficial trait

12. Natural Selection= Survival of the Fittest
Not necessarily the biggest, strongest, or fastest
Fit to survive that particular environment
Like camouflage

13. Make 2 butterflies that are camouflaged to match their environment.
They must be in plain sight, not under or behind any object
You have to use the template that is provided for you.
Use a SMALL AMOUNT of tape to attach it to the wall or ceiling, etc. Don’t damage my posters when doing this.
You must finish this activity today…no other class time will be allowed.
Lightly put your name and class period on the back, so if yours is NOT found, you will get extra credit.
Tomorrow we will go butterfly hunting!!

14. Charles Darwin accumulated a tremendous collection of facts to support the theory of evolution by natural selection. One of his difficulties in demonstrating the theory, however, was the lack of an example of evolution over a short period of time, which could be observed as it was taking place in nature.

15. Although Darwin was unaware of it, remarkable examples of evolution, which might have helped to persuade people of his theory, were in the countryside of his native England. One such example is the evolution of the peppered moth, Biston betularia.

16. Which moth is more likely to be eaten?

17. The economic changes known as the Industrial Revolution began in the middle of the eighteenth century. Since then, tons of soot have been deposited on the countryside around industrial areas. The soot discolored and generally darkened the surfaces of trees and rocks. In 1848, a dark-colored moth was first recorded.

19. Years ago, in some areas, 90% or more of the-peppered moths were dark in color. More than 70 species of moth in England underwent a change from light to dark. Similar observations have been made in other industrial nations, including the United States. With the cleanup of pollution, lighter moths are being seen again.

20. So, the experiment of the peppered moth proves that changes in a species can happen quickly, given the perfect conditions, which is what Darwin had proposed. This is his proof!