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Unit Title Understanding evolutionary relationships (for majors introductory biology)

Understand how phylogenetic trees are constructed and interpreted for addressing biological questions. Engage in activities to evaluate data and develop evolutionary hypotheses using amino acid sequences and evolutionary processes.

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Unit Title Understanding evolutionary relationships (for majors introductory biology)

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  1. Unit Title Understanding evolutionary relationships (for majors introductory biology) Learning goals 1) Understand how phylogenetic trees are constructed 2) Understand how to interpret phylogenetic trees 3) Understand how scientists use phylogenetic trees to address a variety of questions in biology

  2. Learning Outcomes HOC LOC

  3. What students will already know • Understand that shared derived similarities are used to select among trees • Know basic vocabulary associated with phylogenies • Have built phylogenies using morphological traits as characters • Know that sequences can be used as characters • Have seen convergent evolution in a morphological context Understanding phylogenies Convergent evolution

  4. Tidbit Instructions • Each person has • 6 amino acid sequences • Each sequence represents a species. All students are working with the same 6 species and all are numbered the same way. • 3 phylogenetic hypotheses • these are only three of a large pool of possible phylogenies! • To do individually: • Arrange sequences based on similarity • Select the phylogenetic hypothesis that best matches the data • After 5 minutes each person will vote on their best supported phylogenetic hypothesis • Clicker Vote

  5. Discuss! 4 • Discuss your answer in your group; what strategy did you use? • Do you want to change your answer? Two minutes! • Clicker Revote • Second clicker results 1

  6. Species Key species 1 = Human 2 = Sperm Whale 3 = Dolphin 6 = Horseshoe Bat 4 = Dog 5 = Fruit Bat • write the species names out on the tips of your best-supported tree

  7. Species Key species 1 = Human 2 = Sperm Whale 3 = Dolphin 6 = Horseshoe Bat 4 = Dog 5 = Fruit Bat • pair with someone from a group that chose another phylogeny to identify possible reasons for differences• first pair to explain the disparity wins a prize!

  8. Back in your group, take five minutes to brainstorm about why data from these two genes might support different hypotheses and write list on the board • What kind of evidence would help you distinguish between your different ideas? • Feel free to ask the instructors questions

  9. Two genes determine different phylogenetic relationships • Hemoglobin • Transports oxygen in Red Blood cells • Highly conserved • Prestin • Inner ear motor protein • Role in high frequency sound detection • Certain variants important in acquisition of echolocation www.cell.com news.rice.com

  10. Take a minute to think about this clicker question… What evolutionary process best explains this dichotomy? A. convergent evolution in prestin; echolocation evolved twice B. convergent evolution in globin; echolocation evolved once echolocation echolocation echolocation

  11. Follow-ups • Homework Assignment • Isomorphic problem in a socially relevant system • Summative assessments

  12. Thank you!

  13. Summative assessments (some examples) -- essay question: given a few trees and some data (either genetic or morphological), select the best hypothesis (tree), and defend your choice (Learning Outcome 1,2) -- essay/diagram question: given a phylogeny of a group of organisms, what can you infer about the common ancestor of taxa X and Y with respect to a particular character? (Learning Outcome 3) --Alternatively, given a phylogeny make inferences about the number of gains or losses of a trait (Learning Outcome 4) -- short answer/matching: given a phylogenetic tree, answer some questions identifying sister taxa, common ancestors, clades ,etc. (Learning Outcome 3)-- essay question: design a forensic study to determine the source of an infective virus or bacterium, or the identity of a fish or other food source, using phylogenetic tools (Learning Outcome 5)

  14. Unit Learning outcomes Students will be able to: 1) Use data to evaluate phylogenetic hypotheses 2) Explain why phylogenetic trees are hypotheses, not observations 3) Describe evolutionary hypotheses depicted by a phylogenetic tree. 4) Map evolution of a character on a tree and reconstruct ancestral traits. 5) Apply evolutionary trees to address a contemporary problem

  15. Unit Learning outcomes Students will be able to: 1) Use data to evaluate phylogenetic hypotheses 2) Explain why phylogenetic trees are hypotheses, not observations 3) Describe evolutionary hypotheses depicted by a phylogenetic tree. 4) Map evolution of a character on a tree and reconstruct ancestral traits. 5) Apply evolutionary trees to address a contemporary problem

  16. Unit Learning outcomes Students will be able to: 1) Use data to evaluate phylogenetic hypotheses 2) Explain why phylogenetic trees are hypotheses, not observations 3) Describe evolutionary hypotheses depicted by a phylogenetic tree 4) Map evolution of a character on a tree and reconstruct ancestral traits 5) Apply evolutionary trees to address a contemporary problem

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