1. Evolution Notes Part 2

2. III. Mechanisms of Change – How does evolution happen?
*Old Theory – organisms changed based on a “goal” Ex: giraffes stretched their necks to reach leaves
Lamarck

3. Natural Selection – Darwin’s conclusion
1. Organisms best suited (adapted) to their physical environment survive to pass along their genes to the next generation
a. Natural selection happens at the gene level

4. 2. Nickname: “Survival of the Fittest” Fitness: An organism’s ability to survive in its environment and pass along its genes *Does NOT have to mean: stronger, bigger, etc.

6. 3. Organisms that survive selective pressures (disease, predators, natural disasters, etc.) will pass along their genes

7. 4. Environments change and have different selective pressures, so new species evolve over time a. There is no “end goal” in evolution!

9. 5. Genetic variation in nature provides a range of traits to choose from during natural selection Ex) leg length in deer Ex) shoe sizes in a class

10. 6. Populations of organisms evolve – not individuals
6. Populations of organisms evolve – not individuals *The percentage of alleles in a population changes based on which is best adapted for environment

11. Antibiotics http://www.youtube.com/watch?v=D_yEP91z8Vk

12. What is wrong with the way this cartoon shows evolution?
How does it really work?

13. How do natural selection and evolution really work?
Explain to the cats why they can’t make themselves have an adaptation to open cans

14. Name some adaptations you see here and how natural selection can explain them

15. How about these?

16. B. Sexual Selection
1. A process of selection based on traits that give an organism an advantage in finding a mate and passing on its genes

17. 2. Males are usually the ones who display unusual traits to attract females. Ex) Peacock’s feathers, lion’s mane, etc.

18. 3. Traits good for sexual selection may be bad for natural selection
3. Traits good for sexual selection may be bad for natural selection! Called the “Handicap principle.” Ex) Flashy colors, large clumsy feathers, bird songs, etc. May show that: “I am so healthy I can survive with this handicap - I’m a good mate, I have good genes!”

19. Sexual Selection Video
Watch for some of the adaptations you see in the birds that are useful for sexual selection (and maybe bad for natural selection?)

20. C. Artificial Selection
1. Process of selection in which humans choose which traits are passed to offspring *Helped Darwin make his theory of natural selection

21. 2. Used in crops, livestock, pets

22. 3. Because of the variation of a trait within a species, we can choose the variation we want to increase Ex) Choose the biggest puppies to breed next time – gradually you will get bigger dogs

24. Artificial Selection video
Silver foxes: Real experiment over the last ~50 years
How did humans change the foxes?
(starts at 13:30 min)
(start at 3:40)

25. Foldable Take 1 folder for you and your partner Get scissors & glue
Cut three tabs on the front cover
Place mechanism name on front
Definition inside
Example on inside flap
Title on the back with your names
Due today!