BSCI106 Phylogeny Terms

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BSCI106 Phylogeny Terms
2015-11-15 19:42:22
phylogeny terms
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  1. phylogenetic tree
    shows how a set of organisms are related to each other
  2. nodes
    point at which multiple branches flourish out on the tree, implying a common ancestor
  3. length of branches
    • Either
    • - corresponds to genetic difference between organism and ancestor
    • - has no meaning( does not show time, only convenience)
  4. character
    genetic and measurable trait  in an organism
  5. character state
    variant of character (color, shape, presence,etc)
  6. ancestral similarity
    character state in the common ancestor of all the considered populations of the tree
  7. derived trait
    character state that is changed from the ancestral similiarity
  8. shared derived similarity
    derived form that is shared by two or more populations that inherited the trait from their ancestor

    only useful traits to evaluate
  9. ancestral and derived relationship?
    derived traits can be ancestral on a smaller tree and ancestral traits were once derived on a larger tree
  10. convergent similarity (analogous characters)
    two seperate lineages derive the same trait on accident
  11. synapomorphy
    shared derived trait which is passed down to all further organisms in the lineage
  12. outgroup
    one or many organisms thought to be cloesly related to the group under study but not part of it. Also thought of as the next branch earlier on the tree
  13. principle of parsimony
    the most likely tree has the fewest number of changes in character state