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Mechanisms of Change: Selection

Mechanisms of Change: Selection. Unit 5 – Lecture 3. Types of Evolution. Macroevolution change of one kind of organism into another “macro” = large this has not been observed, but is assumed in the current evolutionary theory. Types of Evolution – cont’d. Microevolution

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Mechanisms of Change: Selection

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  1. Mechanisms of Change:Selection Unit 5 – Lecture 3

  2. Types of Evolution • Macroevolution • change of one kind of organism into another • “macro” = large • this has not been observed, but is assumed in the current evolutionary theory

  3. Types of Evolution – cont’d • Microevolution • small changes in organisms through selection • “micro” = small • has been observed • is assumed in in current evolutionary theory to accumulate until a large change is seen

  4. Discuss • Explain the difference between macro- and micro- evolution

  5. Selection • Example to be used: • A colony of clams lives at a particular beach. These clams come in three varieties – white, grey, and black. Grey is, of course, an intermediate color between the two extremes, white and black. These clams are a part of a sea-bird’s natural diet – however, they are unable to see the clams well which blend into the background of the sand and rock underneath. The beach contains areas of light, dark and intermediate sand in various amounts.

  6. Natural Selection • Natural Selection – organisms which have the best-suited traits survive in their environment

  7. Natural Selection – cont’d • Natural Selection – organisms which have the best-suited traits survive • Four types: • directional selection • one extreme of a trait is best and is selected

  8. Natural Selection – cont’d • Natural Selection – organisms which have the best-suited traits survive • Four types: • disruptive selection • multiple extremes of a trait are best and are selected

  9. Natural Selection – cont’d • Natural Selection – organisms which have the best-suited traits survive • Four types: • stabilizing selection • intermediate/average form of trait is selected

  10. Natural Selection – cont’d • Natural Selection – organisms which have the best-suited traits survive • Four types: • sexual selection • presence of a trait influences mating • trait can be physical OR behavioral I made these just for YOU! La la la la la la la la laaaaaa!!!!!!

  11. Discuss • Name and describe the four types of natural selection. • Give an example of each typeof selection [NOT my example – pick another]

  12. Artificial Selection • Artificial Selection – humans select desirable traits and breed out non-desirable traits • crop farming

  13. Artificial Selection – cont’d • Artificial Selection – humans select desirable traits and breed out non-desirable traits • animal breeding

  14. Discuss • What is the difference betweennatural and artificial selection?

  15. Selection – cont’d • Selection works on POPULATIONS not on individuals • we do not select the best corn plant just to plant one seed and make one plant!! • just so, one animal with new characteristics must cause change to the entire population for it to make a difference

  16. Homework • Complete the Darwin’s Five points worksheet • title of worksheet = “Natural Selection” • Label your MATERIALS check list with 2/8 • material = 3 Tabs • Take our your transcript, I will call you up in a minute.

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