Chapter 4 - Chapter 4 The tree of life how biologists use phylogeny to reconstruct the deep past Darwin viewed evolution as a branching process As buds

Chapter 4 - Chapter 4 The tree of life how biologists use...

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Chapter 4 The tree of life: how biologists use phylogeny to reconstruct the deep past
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Darwin viewed evolution as a branching process “As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its ever branching and beautiful ramifications.” – Darwin, 1859
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Phylogeny:
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A phylogeny is similar to a family tree
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Reading a phylogenetic tree Taxa can be rotated around nodes and still depict the same relationships
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Phylogenies may be drawn in different styles
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No currently existing species is ancestral to any other
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Trees can be drawn with fewer species
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Life is organized in a nested hierarchy
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Taxonomic units legitimate only if they represent a clade
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Some Linnean classifications are not monophyletic
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Synapomorphies identify clades Synapomorphy: shared derived character state Outgroup: used to infer what is ancestral and what is derived
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Reconstruction of phylogenies is based on analysis of characters
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