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5 to 100 million species of organisms on Earth. All organisms on Earth are genetically related. “Tree of Life”. All organisms are genetically related. Eukaryotes. Archaea. Bacteria. P HYLOGENY History of lineages changing through time. NSF Assembling the Tree of Life (ATOL) Program.
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“Tree of Life” All organisms are genetically related Eukaryotes Archaea Bacteria
NSF Assembling the Tree of Life (ATOL) Program “Increased knowledge of phylogenetic relationships will improve human health, push the frontiers of comparative developmental biology, meet threats to agriculture and forestry from invasive species and pests, and improve management of our natural resources.” http://atol.sdsc.edu
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Leaf pages Bembidion zephyrum Rosa davurica Insects Branch pages Eukaryotes Life on Earth The structure of the Tree of Life web site illustrates phylogenetic relationships
Reconstructed Tree A D A D B C many informative changes B C few informative changes Homoplasy in Sequence Data:Long Branch Attraction True Tree
How to avoid long branch attraction? • Exclude long-branch taxa • Exclude characters that show evidence of excessive homoplasy • Use other inference methods that take branch lengths into account • Split long branches by adding more taxa