Bio 20c 2nd midterm

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  1. speciation definition
    Formation of new species from ancestral species
  2. 2 components of speciation
    genetic(reproductive) isolation 

    genetic divergence
  3. what are the 3 different species definition
    bilogical species

    morphological species

    phylogenetic species
  4. biological species (and disadvantage)
    Reproductively isolated 

    members of a species can interbreed and produce viable offspring 

    Disadvantage: can't apply to fossils and asexual organism 

    cant apply to geographically isolated population
  5. Morphological species (advantage and disadvantage)
    based on morphology (structure and shape)

    • Advantage 
    • Widely applicable to fossils and both sexual and asexual organisms 

    • Disadvantages 
    • Criteria subjective (how much difference is enough)
  6. phylogenetic species (advantage and disadvantage)
    based on ancestral analysis (phylogeny)

    • Advantage 
    • Widely applicable

    • Disadvantage
    • Few thorough phylogenies available
  7. Allopatry
    Population physically separated
  8. Sympatry
    Co-occuring population become reproductivly isolated
  9. 2 basic types of reproductive isolation

  10. prezygotic reproductive barriers (example)
    never formed (isolation)
  11. postzygotic reproductive barriers (example)
    formed but not viable (hybrid)
  12. causes of prezygotic isolation




    gametic barriers 

    mechanical incompatibility
  13. Causes of postzygotic isolation
    result when sufficient genetic divergence of isolated population has occurred 

    hybrid viability- zygote fails to survive

    hybrid sterility- offspring cant reproduce
  14. what is anagenesis
    when one species gradually transforms into another

    it doesnt add a branch to a phylogeny
  15. what is cladogenisis
    one species gives rise to 2 and more species 

    add a new branch to phylogeny
  16. 2 basic type of specification
    allopatric speciation

    sympatric speciation
  17. where does allopatric speciation occur
    occurs between geographically isolated population 

    all=other patric= country
  18. where does sympatric speciation occur
    occurs without physical isolation
  19. Allopatric speciation
    pops become geographically isolated 

    gene flow stops between them

    2 basic type of allopatric speciation


    vicariance (barrier rises up)
  20. Sympatric Speciation
    speciation without geographic isolation
  21. what is polyploidy
    special case of sympatric speciation 

    when more than 2 homologous chromosome usually caused by a mutation creates extra chromosomes
  22. autoploidy
    mutation = double chromosome 

    can only self fertalize to produce viable offspring
  23. alloploidy
    2 different species with double chromosomes mate 

    offspring later then self fertilizes
  24. hybrids (when they can and can't form)
    • formed when isolated population reconnect
    • -if sufficient genetic divergence has occurred they are 2 separated species
    • -if recently separated the lack of genetic divergence should allow gene flow
  25. hybrid zone
    area where overlap of separated species occur 

    if hybrid fitness is lower than either parent species then there will be a narrow hybrid zone 

    • if hybrid fitness is higher then it can lead to extinction of species with lower fitness 
    • Example: townsend and hermit warbler
  26. 2 views of the pace of evolution
    Gradualism: genetic change continuous

    punctuated equilibrium: change occur in short burst, long period of little change
  27. Cambrian explosion
    major radiation of multicellular animals

    beginning of Paleozoic era 

    occurred 40-50 mill years 

    almost every modern phylum appears during this time
  28. Homeotic Genes
    aka hox gene 

    control development 

    are turned on/off by their own regulatory genes
  29. phylogenies
    phylogenies = evolutionary history for group of organism (usually depicted as a tree)
  30. phylogenetic tree
    has 3 basic components(branches, nodes, and tips)
  31. what are the 3 types of pylogenetic group


  32. monophyletic group
    true clade: has ancestors and all of its descendent
  33. paraphyletic group
    group with common ancestor but has only some of its decendents
  34. polyphyletic group
    groups of species with different common ancestors
  35. adaptive radiation
    appears in phylogenies as polytomies (star phylogenies)

    represents a period of rapid speciation
  36. 3 potential mechanism for adaptive radiation

    morphological innovation= allows new resources to be exploited

    mass extinction
  37. inputs used to create phylogenies
    comparative anatomy/embryology 


    fossil record

    comparative molecular biology
  38. fossil deffinition
    physical trace of organism that lived in the past (can be dated through radioisotopes)
  39. the 4 basic types of fossils
    • intact: example amber 
    • compression: compression (usually an impression)

    cast: tree branch 

    permineralized: example petrified wood
  40. cladistics
    used to estimating phylogeny

    (chart thingy)
  41. the 1st steps for producing life on earth (3 theories)
    formation of primordial soup 

    reducing atmosphere:(low oxygen, rich in other chemicals and had lots of energy, it was because of that organic molecules were formed)

    extraterrestrial: organic compouds delivered via asteroid

    deep sea vent: organic compounds formed at hydrothermal vents
  42. 2nd step for producing life on earth
    formation of organic polymers

    clay surfaces may have served as templates which the first amino acid polymers formed
  43. 3rd step for producing life on earth
    formation of protobionts (first living thing)

    protobionts had a boundary, polymers inside, enzymatic action, and replicated
  44. 4th step for producing life on earth
    chemical selection 

    new protobionts with enhanced enzymatic or replicating abilities favored
  45. 5th step for producing life on earth
    RNA turned into DNA
  46. 4 major eons in earths history
    • Hadean: formation of earth
    • Archaen: origin of life 

    • Proterozoic: origin and radiation of
    • eukaryotes and simple celled organism  

    • Phanerozoic: radiation and diversification of
    • multicelluar organism
  47. major events of precambrian
    origin and radiation of prokaryotes 

    1st simple multicellular organism
  48. major event of paleozoic
    cambrian explosion

    1st vertebrates (fish) 

    invasion of land and extensive fern forest

    1st amphibions reptiles insects and gymnosperms
  49. Cambrian explosion
    rapid apperance during paleozoic 

    happened withing 40 million years
  50. major events of mesozoic
    first dinosaurs.mammals 

    • first flowering plant
    • mass extinction at end of cretaceous
  51. major events of cenozoic
    • radiation of flowering plants/insect and mammals 
    • appearance of hominids
  52. mass extinction (definition and the main 2)
    happen when 60% of species go extinc in 1 million years 

    Permian extinction: largest one, 90-95% loss, potential causes are rapid climate shift and massive volcanic eruption

    cretaceous extinction: 65 mya, 85% loss, massive meteor impact in the yucatran
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Bio 20c 2nd midterm
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