Understanding evolutionary relationships 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

Learning Outcomes Use data to evaluate and defend phylogenetic hypotheses Describe relationships and evolutionary histories depicted in a tree Understand the vocabulary of evolutionary trees HOC LOC

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

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

Discuss! 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 4 1

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

Species Key species 1 = Human 2 = Sperm Whale 3 = Dolphin 4 = Dog 5 = Fruit Bat 6 = Horseshoe 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!

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

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

What evolutionary process best explains this dichotomy? 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

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

Thank you!

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)

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

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

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