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Phylogenetic Trees

This article explores the key differences between ancestral and derived traits in phylogenetic trees. Ancestral traits represent characteristics of ancestors and are often simpler, akin to prokaryotes, whereas derived traits are those found in organisms but not in their common ancestor, reflecting more complex evolutionary developments similar to eukaryotes. Cladistics is discussed as a method to establish relative timing of divergences, providing insights into evolutionary relationships. Key tools for building cladograms include characters, morphology, embryology, and genetics.

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Phylogenetic Trees

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  1. Phylogenetic Trees

  2. Ancestral Vs Derived • Ancestral: • Trait of the ancestor • “Older model” • Often less complex • Like the prokaryotes • Derived: • Trait that is present in the organism, but not in the common ancestor (of the group being considered). • “New and Improved Model” • Not always more complex, but usually • Like Eukaryotes

  3. Cladistics • What: • Used to determine relative timing of divergences. • Why? Because it tells us about who evolved when • The hierarchy, or ranking, of groups derives logically from their genealogical position. • Example:

  4. Cladistics • Tools: (WHAT DO YOU USE TO BUILD ONE?) • Characters/Morphology • Embryology • Genetics (molecular tools) • Example:

  5. Embryology

  6. Embryology

  7. How to Build a Cladogram Eyes • http://ccl.northwestern.edu/simevolution/obonu/cladograms/Open-This-File.swf • Cladogram by Brightstorm: http://www.youtube.com/watch?v=3DxNwzzjm_4 Eyes Eyes Eyes Eyes

  8. Charophytes Green Algae • Spirogyra, stonewoand desmids are all members of this fresh-water group of "green algae". • The base of the plant family

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