1. The Theory of Evolution

2. 2 views of evolution Microevolution – Small changes over SHORT periods of time – Supports improvements in existing species Macroevolution – Small changes accumulating over LONG periods of time result in major changes – Supports the formation of new species Evolution – changes in a population over time

3. 3 types of evolution: 1.Divergent – similar organisms become increasingly different because of different types of environments

5. 3 types of evolution: 2. Convergent - different organisms become increasingly similar because of similar types of environments

6. 3 types of evolution: 3. Coevolution - two nonrelated species change because of the close interaction ex. predator/prey ex. plant/pollinator

8. Cladogram Diagram showing evolutionary relationships based on similar characteristics Usually shows divergent evolution Which are more related? crocs and rabbits or crocs and birds Which organism is the most “primitive” (evolved earliest)?

9. What causes evolution to happen? 1.NATURAL SELECTION*** (“survival of the fittest”)

10. Development of the Natural Selection Theory 1700s – Lamarck was the first person to state that organisms change over time and that new organisms are modified descendants of older organisms (with his theory of acquired traits)

11. Development of the Natural Selection Theory 1800s – Charles Darwin sailed on the H.M.S. Beagle and gathered data from organisms (fossils, finches, etc.)

12. From this data, Darwin inferred that all species had descended from one or few original types of life Darwin also concluded that the way species/organisms change over time was by natural selection

13. The Process of Natural Selection There must be variation in the traits of a population. (This variation is caused by organisms having different genes.)

14. The Process of Natural Selection There must be environmental pressures that favor one variation of the trait over the other.

15. The Process of Natural Selection Organisms with the better traits will survive better and longer, reproduce, and pass those good traits on to their offspring. The result will be a population better suited for the environment.

16. What causes evolution to happen? 2.Geographic isolation organisms of a population can become isolated from one another by a geographic barrier if they are no longer able to reproduce, they may become two separate species the formation of a new species is called speciation

17. What causes evolution to happen? 3. Artificial Selection Humans cause evolution to happen because we “choose” which traits to select for Examples: – Breeding dogs to have desirable traits – Genetic engineering