Tree-thinking_A_key - Phylogenetic Trees Name _ 26 April...

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1 Phylogenetic Trees Name __________________________ Name __________________________ 26 April 2011 Name __________________________ The table below summarizes key traits found in some major groups of animals that have vertebrae, or backbones. A “1” indicates that the trait is present; a “0” indicates that it is absent. Assume that each of the traits is homologous in the groups listed—for example, that the limbs of lizards and mammals are derived from limbs found in a common ancestor. Internal bone Limbs Amniotic egg Fur, lactation Scales with keratin Lizards 1 1 1 0 1 Ray-finned fish 1 0 0 0 0 Mammals 1 1 1 1 0 Snakes 1 0* 1 0 1 Amphibians 1 1 0 0 0 *Note that some snakes have vestigial hindlimbs as embryos or as adults. Use these data to estimate the phylogeny of the groups. Here’s one way of getting started: 1. Note that only lizards and snakes have scales with keratin—meaning that they should be found next to each other on the tree, joined by a common ancestor that had scales with keratin. In the space to the right, start your tree by connecting lizards and
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Tree-thinking_A_key - Phylogenetic Trees Name _ 26 April...

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