1. Natural Selection

2. Species Vary Globally
Similar animals (different species) , different locations in world, similar habitats
Rheas Ostrich Emu
South America Africa Australia

3. Species Vary Locally
Different islands had different varieties of Finches.
Their beak shape differed based on what their diet, (fruit, nuts, insects, etc).

4. Species Vary Over Time
Some fossils of extinct animals were similar to living species.
The long-extinct glyptodont, a giant armored animal similar to the armadillo.

5. Creates Natural Selection

6. 1. There is variation within a. population (from inherited traits –
1. There is variation within a population (from inherited traits – mutations!)

7. Some variations are favorable

8. More young are produced than can survive (many die of disease, starvation, predation)

9. 4. Those most likely to survive and reproduce are the individuals with the favorable variations (and their offspring are more likely to inherit those favorable variations as well)

10. 5. Over time, changes can accumulate and populations can change.

11. Selection Pressures – things in an environment that make one variation favorable over another

12. Gene Pool – all of the genes in a population

13. Common Descent – all species, living and extinct, are descended from ancient common ancestors

14. 3 Types of Natural Selection
Directional Selection – population shifts towards one extreme

15. 2. Disruptive Selection – population moves towards both extremes

16. 3. Stabilizing selection – population narrows to center