Introduction to evolution Introduction to phylogenetic trees Build a phylogeny 1 Build a phylogeny 2 Applying phylogenetic trees Learning objectives Be able to read a phylogenetic trees and predict evolutionary relationships ID: 1011652
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1. ScheduleCultural connection Introduction to evolutionIntroduction to phylogenetic treesBuild a phylogeny 1Build a phylogeny 2Applying phylogenetic trees
2. Learning objectivesBe able to read a phylogenetic trees and predict evolutionary relationshipsBe able to construct phylogenetic trees and use parsimony to evaluate which tree is the most likelyBe able to identify shared derived traits and distinguish this from convergence.
3. What is it?Is it controversial? If so, why?Do scientists think it is controversial?Evolution
4. Any change in the inherited traits of a population that occurs from one generation to the next The process of descent with modification that is responsible for the origin, maintenance and diversity of lifeEvolution
5. 5Biodiversity 1,700,000 described (and climbing)conservative estimate is that only 1/3 are described > 5,000,000 speciesNote our accuracy in estimates for most taxa is very lowFor example there are ~ 10,000 species of birds23 new bird species described in 2013!- Junin Tapaculo found in the Andes in Peru
6. Broad applicationsMedical research and public healthPersonalized medicineDevelopment of vaccines & therapeutics AgricultureIncrease genetic diversityInclude refuge areaEcology and conservationCaptive breedingInbreeding depression
7. Patterns of change through timeEvolutionDescent with modificationPhenotype time
8. PhylogeneticsPhylogeny: A visual representation of the evolutionary history of populations, genes, or species.Phylogenies represent hypotheses about evolutionary relationships that we can test by collecting more data
9. More closely related species should share more traits in commonPhylogenetics
10. Reading phylogenetic trees
11. Reading phylogenetic treesTrees can be rooted or unrootedBirdsCrocodilesTurtlesAmphibiansMammalsLizardsSnakesBirdsCrocodilesTurtlesAmphibiansMammalsLizardsSnakesan unrooted tree shows relationships, but not timeroot establishes a point of common ancestry - outgroupwhere the root is put can drastically change the meaning of the tree root
12. ABCABCtrees can be slanted or bracket styleReading phylogenetic trees
13. Trees can be oriented in different ways, but the relationships remain the sameBirdsCrocodilesTurtlesAmphibiansMammalsLizardsSnakesBirdsCrocodilesTurtlesAmphibiansMammalsLizardsSnakesReading phylogenetic trees
14. BirdsCrocodilesTurtlesAmphibiansMammalsLizardsSnakesTurtlesAmphibiansMammalsLizardsSnakesCrocodilesBirdsTaxa can rotate around interior nodes without changing the relationshipsReading phylogenetic trees
15. BirdsCrocodilesTurtlesAmphibiansMammalsLizardsSnakesTurtlesAmphibiansMammals LizardsSnakesCrocodilesBirdsTaxa can rotate around interior nodes without changing the relationshipsReading phylogenetic trees
16. BirdsCrocodilesTurtlesAmphibiansMammalsLizardsSnakesTurtlesAmphibiansMammalsLizardsSnakesCrocodilesBirdsTaxa can rotate around interior nodes without changing the relationshipsThe order of branching is importantReading phylogenetic trees
17. Are these two trees equivalent?
18. Is the frog more closely related to the fish or the cat?
19. Constructing phylogeniesgroups species based on shared characters “Shared”: All (or most) members of the group and their common ancestor have the trait
20. Constructing a phylogeny
21. Constructing a phylogeny
22. Constructing a phylogeny
23. How do we pick the best tree?In general, parsimony is our guide Fewest evolutionary changes necessary to explain the dataSome datasets can’t generate one best tree
24.
25. Candy PhylogenyStep 1: Pick traits (1= has the trait, 0= does not have the trait)Step 2: Now draw 2 hypothetical trees. Do not worry about whether it is the best tree. Step 3: Now map each of your traits onto the two trees. Put a plus or minus to indicate whether it is a gain or loss of the trait. Step 4: Use parsimony to evaluate which is the better tree.
26. Homologous vs. convergent characters
27. Not all shared traits are due to common descentConvergence: character state similarity not due to common descentImaging forming camera eye similar in octopuses and other vertebrates
28. Not all shared traits are due to common descent
29. Not all shared traits are due to common descentParsimony is used to select the best tree – 2 vs 6 changes!
30. Broad applicationsMedical research and public healthPersonalized medicineDevelopment of vaccines & therapeutics AgricultureIncrease genetic diversityInclude refuge areaEcology and conservationCaptive breedingInbreeding depression
31. Broad applicationsWhere did HIV come from?When were cows domesticated?Do different populations of elephants require conservation?
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33. Bos taurusBos indicusEach species was a separate domesticationevent
34. Conservation application