Tree-thinking_B_key - Phylogenetic Trees Name 26 April 2011...

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1 Phylogenetic Trees Name __________________________ Name __________________________ 26 April 2011 Name __________________________ The tree to the right shows the Urochordates best current estimate of the evolutionary relationships among Sharks & rays the vertebrates—the animals with backbones. The tree also shows an Amphibians outgroup called the urochordates. Urochordates don’t have backbones. Lizards Snakes 1. Add a vertical bar to the tree and label it “Vertebrae”, at the point where Mammals vertebrae evolved in an ancestral population. Ray-finned fish Hagfish 2. Amphibians, lizards, snakes, and mammals all have limbs (or evidence that their ancestors had limbs). Add a vertical bar to the tree and label it “Limbs,” at the point where limbs evolved in vertebrates. 3. Which group is most closely related to the hagfish: lizards or urochordates? (This is the same as asking which of the two groups shares a more recent common ancestor with hagfish.) Explain your reasoning. Lizards, because they share a common ancestor with hagfish at the node marked with a fat arrow.
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This note was uploaded on 01/25/2012 for the course BIOC BIOC 405 taught by Professor Brockerhoff during the Spring '09 term at University of Washington.

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Tree-thinking_B_key - Phylogenetic Trees Name 26 April 2011...

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