1. Natural Selection: the mechanism for evolution

2. Charles Darwin (1809 – 1882) I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection. - from The Origin of Species

3. Darwin’s Voyage of Discovery A reconstruction of the HMS Beagle sailing off Patagonia.

4. The Voyage of the Beagle

5. Galapagos Islands http://vimeo.com/17051816 http://app.discoveryeducation.com/player/vi ew/assetGuid/9E8DE1D4-BCBD-422C- B307-E79CA309E95Chttp://app.discoveryeducation.com/player/vi ew/assetGuid/9E8DE1D4-BCBD-422C- B307-E79CA309E95C

7. Natural Selection: Nature acts as the “selecting” agent.  Organisms better adapted (most “fit”) to the environment survive and reproduce more successfully.

8. 1. VARIATION - Individuals of a population vary in their characteristics (different color, muscles, eyesight, etc.) HOW DOES THIS OCCUR?????? STEPS of Natural Selection :

10. 2. OVERPOPULATION – A population produces more offspring than can survive

12. 3. COMPETITION – Because of over population, there is competition - “struggle for existence” between organisms for food, space, water, etc.

14. 4. Heredity “ DIFFERENTIAL REPRODUCTIVE SUCCESS” Individuals with best suited traits to the environment are more likely to survive and reproduce more offspring, passing the helpful variations on in the population.

15. 5. SPECIATION – over long periods of time, variations accumulate and become so numerous that the population represents a new species.

16. Artificial Selection Humans “select” which organisms breed (humans act as selecting agent instead of nature)

18. Selection Pressures Factors that cause “selection” to occur: Amount of food available Water Shelter Predation (predators hunting a population) Disease Humans…?

19. Evolution is the progressive change in populations of organisms over time through the process of natural selection. It explains how biodiversity is achieved.

20. How does evolution really work? Video and Questions: http://www.pbs.org/wgbh/evolution/educators/cou rse/session4/explore_a.html Evolution of Camouflage Video: http://www.pbs.org/wgbh/evolution/educators/cou rse/session4/explore_b.html http://www.pbs.org/wgbh/evolution/educators/cou rse/session4/explore_b.html http://app.discoveryeducation.com/player/view/assetGuid/12302FAB-8366-4FCE- BF17-7A75F5700B4D