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2011-03-07 22:44:13
biology micro evolution

Chapter 17 of the biology book that discusses micro-evolution
Show Answers:

  1. What is the smallest unit that evolves?
  2. alleles
    the variant forms in which genes exist

    • no more than 2 for a given gene
    • -one from the mother
    • -one from the father
  3. Gene pool
    The sum total of alleles in a given population
  4. Basis of evolution is...
    a change in the frequency of allels in a gene pool
  5. Micro-evolution
    a change of allele frequencies within a population over a relatively short period of time.

    these changes in alleele frequencies can said to have evolved
  6. What are the 5 agents of micro-evolution?
    • -mutation
    • -gene flow
    • -genetic drift
    • -sexual selection
    • -natural selection
  7. Mutation
    Permanent alteration in an organism's DNA

    Some mutations are heritable, meaning they can be passed on from one generation to the next.
  8. Gene flow
    Movement of genes from one population to another

    through migration: movement of individuals from one population into the territory of another
  9. Genetic drift
    chance alternation of allele frequencies in a population

    • has greatest effects on small populations
    • -bottleneck effect
    • -the founder effect
  10. Sexual selection
    form of natural selection that can affect the frequency of alleles in a gene pool

    occurs when differences in reproductive success arise becuse of differential success in mating
  11. Natural selection
    • Some individuals more successful than others in surviving
    • -and hence reproducing
    • -owing to traits that better adapt them to their environment
  12. Evolutionary Fitness
    • the phrase "survival of the fittest" is misleading
    • -implies that evolution works to produce generally superior being who would be successful competitors in any environment
    • only has to do with relative reprouctive success of individuals in a given environment at a given time.
  13. What are the three modes of natural selction?
    Stabilizing, directional, diruptive
  14. Stabilizing Selection
    • most common
    • moves a given character in a population toward intermediate forms and hence tends to preserve the status quo
  15. Directional Selection
    moves a given character toward one of its extreme forms
  16. Disruptive Selection
    • moves a given character toward two extreme forms
    • (rarest form)