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I. Variation A. Variation is the difference in traits because of difference in genes 1. Example: Things that vary in humans 2. What are some things that vary in humans? • • • • • • Height Eye color Hair color Leg length Arm Length Skin color B. Variation can: 1. Hurt an organisms chance of survival • Example: A slow cheetah 2. Help an organisms chance of survival • Example: A fast cheetah 3. Not effect an organisms chance of survival • Example: A fast male cheetah that does not hunt C. Cheetah speed • How did the cheetah become so fast? • http://www.youtube.com/watch?v=P1QxdSTrwwE • With a twist: http://www.youtube.com/watch?v=WiLT-l97FHg II. Adaptation A. Adaptation is an inherited genetic characteristic that improves an organism’s ability to survive in a particular environment B. Cheetah Adaptations • • • • Spotted Sharp claws Long spine Speed C. Polar Bear Adaptations • • • • Big claws White fur Big, sharp teeth Strength D. Seal adaptations • Blubber • Long, slick body • Fins III. Fitness A. Fitness is the ability of an organism to survive and reproduce, passing their genes to the next generation B. Why are faster cheetahs more fit? 1. Some cheetahs are slower and some are faster (variation) 2. Fast cheetahs could catch food better than slow cheetahs 3. More fast cheetahs survived than slow cheetahs (because caught more food) 4. Fast cheetahs passed genes to baby cheetahs 5. Fast cheetah babies IV. Natural Selection A . Natural Selection – the process in nature in which organisms with favorable variations survive, reproduce, and pass their variations to the next generation. 1. Favorable traits survive 2. Unfavorable traits die out B. How Natural Selection Occurs 1. Organisms have variation of traits • Similar organisms are not exactly the same • Example: • Some cheetahs are slower and some are faster How Natural Selection Occurs 2. Organisms struggle to survive a. Struggle with other organisms b. Struggle because of the environment • Example: • Cheetahs need to catch prey (food) to survive How Natural Selection Occurs 3. Some variations help organisms survive such as adaptations • Example: • Faster cheetahs can catch more food than slower cheetahs How Natural Selection Occurs 4. Organisms with best adaptations are most likely to survive to reproduce • Example: • Faster cheetahs are more likely to survive and reproduce (because they catch more food) How Natural Selection Occurs 5. They will pass their genes to next generation • Example: • Fast parent cheetahs will pass their genes on to baby cheetahs How Natural Selection Occurs 6. Over time, there will be more organisms with best adaptations for the environment • Example: • More fast cheetahs survive to have baby cheetahs than slow cheetahs • More fast baby cheetahs are born than slow baby cheetahs How Natural Selection Occurs: Summary 1. Organisms have variation of traits • Similar organisms are not exactly the same 2. Organisms struggle to survive • Struggle with other organisms • Struggle because of the environment 3. Some variations help organisms survive • Adaptations 4. Organisms with best adaptations are most likely to survive to reproduce 5. They will pass their genes to next generation 6. Over time, there will be more organisms with best adaptations for the environment V. Evolution A. Natural Selection causes species to change over time. B. Common WRONG Ideas 1. You can acquire the trait if you need it to survive – NO; if you don’t already have the trait, you die! Populations can and do become extinct. 2. One organism can evolve – NO; evolution is change in a population over time (it may be thousands of years) 3. Evolution is only a theory – NOT entirely; evolution is a SCIENTIFIC theory which means it is supported by mountains of evidence, experimentation, and observations. All of the SCIENTIFIC evidence supports evolution. There is NO scientific evidence that does not support evolution.