Zoo 201 Lec General Terms

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sinopa
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89141
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Zoo 201 Lec General Terms
Updated:
2011-06-04 18:38:17
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zoo lappin evolution
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General terms needed for vertebrae portion of zoology 201
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  1. What are nodes?
    Branch points on a phylogeny tree that represent common ancestors
  2. What is extant?
    moden creatures that still exist today
  3. What are taxa (pl.taxon)
    a way to name a group
  4. What is homology?
    • "same origin in different organisms under every variety of form and function."
    • ex. limb skeleton of various tetrapods share homologous elements
  5. What do homologous structures indicate?
    indicate common evolutionary ancestry and are used to generate phylogenetic hypothese of the relationships among organisms
  6. What is analogy?
    structures that serve similar function but DO NOT indicate common ancestry
  7. Define cladogram
    phylogeny based on cladistic methods
  8. Defien synapomorphies
    • relationships reconstructed based on shared, derived characteristics.
    • characters used to define synapomorphies are presumed to be homologous across taxa of interest
  9. Define clade
    • a group defined by synapomorphies.
    • ex. Squamata (lizards, snakes, amphisbaenians) all share the Squamata characteristic.
  10. Define monophyletic group
    includes ancestor and all descendents
  11. Define paraphyletic group
    ancestor and somedescendants
  12. Define polyphyletic group
    common ancestor is not included
  13. What do branch points on a phylogeny tree indicate?
    speciation events (formation of a new species)
  14. Define allopatric speciation
    • the dominant mode of speciation,
    • most pervasive.
    • when the population separated into two separate groups by a geographic barrier, then reproductive barriers can evolve
  15. Define adaptive radiation
    • evoltuion of many diverse species from a common ancestral stock, can result from allopatric speciation.
    • typically associated with invasion of areas with unoccupied habitats or "niches"
  16. Define heterochrony
    • evolutionary change in timing of development.
    • ex. humans exhibit extended early development and are born at an early age.
    • ex2. gills of axolotl are retained throughout its life
  17. Define convergence
    • independent evolution of of a similar characteristic (morphology, physiology, ecology, behavior, etc.) in two or more taxa.
    • presence of similarity must NOT be due to common ancestry.
    • analogy is convergence that has a functional explanation in the biology of the organism.
    • ex. wings
  18. What does reduction and loss refer to?
    morphology
  19. What is reduction
    • a reduction in size or prominence of a feature or element.
    • ex. humans have relatively simple skull and jaw structure, an example of simplification in a highly derived taxon.
  20. What is reversal
    • evolutionary return to a condition seen in an ancestor termed "secondarily derived."
    • determined bby analysis within a phylogenetic framework.
    • ex. humans are seconadily derived terrestrial.
  21. What is specialization?
    • morphological, physiological, and/or behavioral modification for a specialized biological role.
    • specializations also sometimes called adapations (determined in phylogenetic framework).
  22. What is parsimony?
    When there are multiple hypothesis, the favored hypothesis iswhatever requires the fewest changes or the least explanation

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