1. Click to edit Master subtitle style 1/7/13 Darwin: Natural Selection & evolution Chapter 6 pgs 172-187 Pgs 728-729

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3. 1/7/13. After Darwin finished public school, he enrolled in college to become a doctor but later studied theology, (religious studies). A professor at Cambridge University in England recommended him for a position on a British Navy survey vessel, the HMS Beagle. Darwin became the naturalist on the voyage which was to last two years. The voyage ended up lasting five years, during which time Darwin was able to explore extensively in South America and numerous islands in the Pacific Ocean, including the Galapagos. Wanting to share his findings, he published a book on his ideas of natural selection and evolution entitled The Origin of Species.

4. 1/7/13 Voyage of HMS Beagle

5. 1/7/13 Darwin’s Observations  Diversity – each area of the world has very different organisms  Fossils – preserved remains of an organism that lived in the past. The fossils Darwin saw looked different than organisms living at that time.  Characteristics of Galapagos Islands organisms – organisms were different from organisms elsewhere and from organisms on other Galapagos islands

6. 1/7/13 Galapagos Islands

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8. 1/7/13 Comparisons Between organisms on the islands Finches

9. 1/7/13 Adaptations  Adaptation – trait that helps an organism survive & reproduce  Examples:  The finches’ beaks  The iguanas’ claws  Poison & bad taste  Bright colors of flowers  Animal coloring

10. 1/7/13 Evolution  Darwin studied his observations for 20 years after returning to England  Reasoned that organisms arriving on Galapagos faced conditions different from on the mainland.  He hypothesized the species gradually changed over many generations & became better adapted to the new conditions.  This gradual change is called evolution.  However Darwin could NOT explain how the changes happened.

11. Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Sevent h Outline Level  Eighth Outline Level  Ninth Outline LevelClick to edit Master text styles  Second level Third level Fourth level  Fifth level 1/7/13 Natural Selection  In 1859, Darwin offered an explanation – evolution occurs by natural selection.  He published his idea in The Origin of Species

12. Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Sevent h Outline Level  Eighth Outline Level  Ninth Outline LevelClick to edit Master text styles  Second level Third level Fourth level  Fifth level 1/7/13 Natural Selection  Natural selection – process by which individuals that are better adapted to their environment are more likely to survive & reproduce than other members of the same species

13. 1/7/13 Natural Selection  Factors that can result in natural selection: 1. Overproduction – produce more offspring than can survive 2. Competition – members of a species will compete for resources 3. Species Variation(aka – speciation) – any difference between individuals of the same species Organisms with a helpful variation will survive & reproduce. Poor variations will die out. Over a long time, natural selection will lead to change.

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16. 1/7/13  Mutualism – relationship in which both species benefit  Commensalism – relationship in which 1 species benefits and the other is neither helped nor harmed  Parasitism – 1 organism lives in or on another organism and harms it  Mutualism – relationship in which both species benefit Commensalism – relationship in which 1 species benefits and the other is neither helped nor harmed Parasitism – 1 organism lives in or on another organism and harms it

17. 1/7/13 Mutualism Parasitism commensalism

18. Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Seventh Outline Level  Eighth Outline Level Ninth Outline LevelClick to edit Master text styles Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Seventh Outline Level  Eighth Outline Level  Ninth Outline LevelClick to edit Master text styles  Second level Third level Fourth level  Fifth level Click to edit the outline text format Second Outline Level  Third Outline Level Fourth Outline Level  Fifth Outline Level  Sixth Outline Level  Seventh Outline Level  Eighth Outline Level  Ninth Outline LevelClick to edit Master text styles  Second level Third level Fourth level  Fifth level 1/7/13 Reasons for Species variation 4. genetic mutation  Darwin knew changes happened, but could not explain how. (1850s) Mendel explained how change happens through genetic traits (1850s)