Darwin’s Theory ( set paper up as shown below using a ruler) Test Questions Teacher NotesPicture (1 per slide) Notes will go in this section

Darwin’s Theory Galapagos Islands

Who is he? December 1831, HMS Beagle (British ship) went on a 5-year trip around the world 22 year old Charles Darwin – naturalist - observed plants and animals - led him to develop the theory of evolution by natural selection

I. Darwin’s Observations Included: 1) the diversity of organisms, 2) remains of ancient organisms, 3) and characteristics of organisms on Galapagos Islands A) Diversity –Saw tremendous diversity –Scientists have now identified 1.7 million species –Def. species: organisms that can mate & produce fertile offspring

Darwin’s Observations (cont.) B) Fossils Def. fossil : the preserved remains or traces of an organism that lived in the past Darwin saw bones of past sloths that were larger than when he lived. Giant Sloth

II. Galapagos Organisms Darwin found similarities between Galapagos organisms & South American organisms A) Comparisons to S. American Organisms –Many similarities as main land –Important differences: –Small number of plants and animals had to reach island IslandsMainland Fed on seaweed Fed on leaves Large clawsSmall claws

Horse, donkey, mule

Galapagos Organisms (cont.) B) Comparisons Among Islands –Saddle shape vs. dome shaped shells for tortoises –The beaks of finches also differed (figure 3 p. 227) C) Adaptation Def. adaptation: a trait that helps an organism survive and reproduce in its environment Examples 1. Beak structure determines type of food. 2. Poisonous or bad tasting milkweed 3. Bright colored flowers attract insects

III. Evolution A) Darwin’s Reasoning 1. Plants & animals on island face environmental factors different from mainland 2. Species gradually change 3. Species become better adapted to new environment Def. evolution: gradual change in a species over time Def. Theory: concept that explains wide range of observations

Evolution (cont.) B) Selective Breeding When humans select a specific trait they want to pass to offspring (ex1) Sheep with fine wool (ex2) Pigeons with more than average number of feathers

IV. Natural Selection Def: individuals that are better adapted to environment and more likely to survive and reproduce Factors that affect process: (fig. 5) 1. Overproduction 2. Variations 3. Competition

Natural Selection (cont.) A) Overproduction only strong survive since there isn’t enough food, water and living space B) Variations slight differences in traits (ex) Insects food choices C) Competition food and other resources are limited

Natural Selection (cont.) D) Selection - some variations make individuals better adapted to their environment - environment “selects” organism with helpful trait - can cause change

Natural Selection (cont.) E) Environmental Factors - can affect organism’s ability to survive (ex1) Copper in soil with monkey flower (ex2) Smoke on trees with moths

Natural Selection (cont.) F) Genes and Natural Selection - variations in organisms can result due to mutations in genes