Inferring Ph logenetic TreesInferring Phylogenetic Trees
T d ’ tiToday’s questions:
I B ildi i lI. Building trees tutorialII. The problem of homoplasy
I. Reading treesHow does this differ from the Great Chain of Being?
I. Phylogenetic trees tutorial
Work in teams of 3. Middle person as the scribe (does the writing). As you work through the questions, bethe writing). As you work through the questions, be sure to explain your logic to each other.
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MonotremesMarsupialsGolden mole, tenrecElephant shrewsElephant shrewsAardvarkElephantsHyraxes
Current
yDugong, manateesArmadillosAnteaterSlothsCurrent
phylogeny of the mammals,
SlothsFlying shrews, tree shrewsProsimiansMonkeys
estimated from DNA sequence data
ApesRabbitsRodentsMoles hedgehogsdata Moles, hedgehogsHyenas, weasels, wolvesSeals, sea lionsPangolinH hiHorses, rhinosCamels, pigs, cowsHippos, whales, dolphinsBats
II. The problem of homoplasy (versus homology)
Examples of traits that are similar, but not because they were inherited from a common ancestor:
• Body shape in dolphins and icthyosaurs• Flippers in penguins and sealsFlippers in penguins and seals• Eye position in crocodiles and hippos• Camera eye in octopus and vertebratesy p
1. Is the fur of chimps and the hair of humans homologous?
2. Whales and dolphins have only traces of fur. Humans p yhave little hair. Are these trait losses homologous?
3. What does the hypothesis of homoplasy predict about genetic and developmental similarity?
What causes homoplasy?
I h l i l t it C t l ti d t• In morphological traits: Convergent evolution due to:
• Reversal (particularly(particularly important in DNADNA sequence data):
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