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Evolution I

Evolution I. Scott Bowling Topher Gee Stan Schneider Beth Schussler Randy Small Min Zhong Facilitator: Paula Lemons. Evolution I. Topic: Evidence for and mechanisms of evolution Introductory Biology (majors), Large enrollment (200+/section) We are assuming students “know”:

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Evolution I

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  1. Evolution I Scott Bowling Topher Gee Stan Schneider Beth Schussler Randy Small Min Zhong Facilitator: Paula Lemons

  2. Evolution I • Topic: Evidence for and mechanisms of evolution • Introductory Biology (majors), Large enrollment (200+/section) • We are assuming students “know”: • Definition of evolution • Hardy-Weinberg Equilibrium and problem solving • Evolutionary processes

  3. Tidbit Learning Goal • Students will demonstrate an understanding of evolutionary processes

  4. Tidbit Learning Objectives • recall Hardy-Weinberg and evolutionary processes Given a scenario, students will: • identify whether evolution has occurred and articulate the evidence • predict the mechanism(s) driving evolutionary change and identify the necessary evidence

  5. Pea plants have two flower colors: purple and white • Trait controlled by one gene: purple dominant to white

  6. Frequency of white flower allele (q) Generation On your own, summarize what this figure is telling you.

  7. Frequency of white flower allele (q) Generation In small groups, share your ideas.

  8. Graph here A B C Frequency of white flower allele (q) • A only • B only • C only • Both A and B • Both A and C • Both B and C • All three regions • None of these regions Look at the shaded Regions (A, B, and C). Over which, if any of these regions has evolution occurred for the flower color gene? Generation

  9. A B C Frequency of white flower allele (q) • Discuss the importance of the following factors in deciding whether evolution has occurred: • Allele frequencies • Number of generations • Magnitude of change Generation

  10. Graph here A B C Frequency of white flower allele (q) • A only • B only • C only • Both A and B • Both A and C • Both B and C • All three regions • None of these regions Look at the shaded Regions (A, B, and C). Over which, if any of these regions has evolution occurred for the flower color gene? Generation

  11. Each group will be assigned one evolutionary process to discuss and explain to the rest of the class: • Genetic drift • Mutation • Non-random mating • Migration (gene flow) • Natural selection

  12. Dr. Sally Slither conducted a study on two populations of lizards: one on an isolated island and the other on the mainland. • Generation time = 2 years • Island population (N = 1,000) • Mainland population (N = 100,000) • In each population, some have googly-eyes (dominant) and some have small eyes (recessive). Googly-eyed Small-eyed

  13. Dr. Slither’s 20-yr study of eye size in lizard populations

  14. Dr. Slither’s 20-yr study of eye size in lizard populations Graph here • Genetic drift • Mutation • Non-random mating • Migration (gene flow) • Natural selection Based on the figure above, what is the most likely explanation for why the island population’s allele frequency is more erratic than the mainland’s?

  15. Googly-eyed lizards are more sensitive to light and prefer dimmer conditions. • The mainland habitat is being deforested by human activity.

  16. Dr. Slither’s 20-yr study of eye size in lizard populations Given what you know, what could explain the mainland population’s gradual shift in allele frequency over time? Genetic drift Mutation Non-random mating Migration (gene flow) Natural selection

  17. Homework • For either lizard population (mainland or island), what evidence would you need to support the hypothesis that EACH of the following is occurring: • Natural selection • Non-random mating • Migration

  18. Summative Assessment A population of spiders includes individuals with plain legs (recessive) as well as individuals with yellow bands on their legs (dominant). You have a data set that spans multiple generations for this population. In the first generation your data indicate that of 100 spiders, 64 had yellow bands on their legs. Five generations later, the population had grown to 10,000 spiders and included 1,600 with plain legs. 1. Has evolution occurred over these generations? Explain your reasoning and show supporting work. 2. Has natural selection occurred on the yellow band phenotype? Why or why not? 3. What data set(s) would you need to collect to identify the mechanism of evolution?

  19. Diversity:

  20. OPTIONAL? What evidence is necessary to know whether evolution has occurred within a population? • Individually, write a one-minute essay • Brief group discussion

  21. The island habitat is undisturbed and heavily forested.

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