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2011-03-07 20:24:42

Patterns of Natural Selection
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  1. Evolution by natural selection occurs when a)______ leads to differential success in b)______ and c)_______.
    a. heritable variation

    b. survival

    c. reproduction
  2. Because of a)______, genetic variation is b)______ in populations.
    a. natural selection

    b. maintained
  3. True or False

    Is lack of genetic variation is usually a good or bad thing?
  4. Genetic variation provides the foundation for a)_____ when environmental conditions b)______.
    a. adaptation

    b. change
  5. Patterns of Natural Selection

    I. Directional Selection

    allele frequencies change in
     Changes the b)______ of a trait
    Tends to c)_____ the genetic diversity in populations by d)_____ one e)_____ over another.
    a. one

    b. average value

    c. reduce

    d. favoring

    e. extreme
  6. Patterns of Natural Selection

    An example of Directional Selection:
  7. drug resistance in certain bacteria
  8. Directional Selection can be a)_____ if environmental conditions warrant such a change.
    a. reversed
  9. An example of reversed directional selection: drop in temperature vs. decline in cliff swallow population
     Known as a)______ directional selection
     Can help b)_____ genetic variation in a population.
    a. oscillating

    b. maintain
  10. II. Stabilizing Selection

    a)_____ extremes in a population are
    b)_____ and the c)______ phenotype is favored
    a. Both

    b. reduced

    c. average
  11. An example of Stabilizing selection:
    Human birth rates
  12. What are the two consequences to stabilizing selection?

    1. a)____ change in the b)______ of a trait over time.
    a. No

    b. average value
  13. What are the two consequences to stabilizing selection?

    2. a)______ in the population is b)_____
    a. Genetic variation

    b. reduced
  14. III. Disruptive Selection

    a)_____ extremes in a population are
    b)_____ and the c)_____ phenotype is selected d)_____.
    a. Both

    b. favored

    c. average

    d. against
  15. Disruptive selection is relatively a)____, but b)_______ in a population in which it occurs.
    a. rare

    b. maintains overall variation
  16. Disruptive selection plays a role in a)_____ – the generation of new b)_____.
    a. speciation

    b. species
  17. II. Genetic Drift

    Any a)____ in the b)______ in a population that is due to c)_____.
    a. change

    b. allele frequencies

    c. chance
  18. Genetic drift causes a)_____ to drift
    b)_____ randomly over time.
    a. allele freqs

    b. up and down
  19. a)______ can be simulated through the flipping of a coin.
    a. Sampling error
  20. Three Important Points about Genetic drift:

    I. a)_____ with respect to fitness. Allele freq changes are not b)_______.
    a. Random

    b. adaptive
  21. Three Important Points about Genetic drift:

    II. Much a)_____ effect in b)_____ pops than in large ones.
    a. larger

    b. small
  22. Three Important Points about Genetic drift:

    III. Can lead to the a)_____ or b)____ of alleles.
    a. random loss

    b. fixation
  23. How do founder effects cause drift?

    Drift occurs when a group of individuals a)______ to a new geographic area and establish a
    a. immigrate

    b. new population
  24. The cause of founder effects on drift:

    If the new population is a)____, allele frequencies will likely be b)______ -this is the founder effect
    a. small

    b. different from the original population
  25. How do population bottlenecks cause drift?

    Sudden reduction in population size caused by stochastic events:
    •  Disease outbreaks
    •  Natural catastrophes
    •  Other random events
  26. Bottle necks:

    Remaining individuals likely have
    a)_____ than the original pop.
    a. different allelic frequencies
  27. III. Gene Flow

    Refers to the a)_____between populations via b)______.
    a. movement of alleles

    b. migration
  28. Gene Flow tends to a)_______ among populations. (lupine example)
    a. equalize allele frequencies
  29. Gene flow is a)_____ with respect to fitness.
    a. random
  30. During gene flow, movement of alleles between pops a)______ between them.
    a. always decreases genetic diffs
  31. During gene flow, human migration across continents is a)______ in human populations.
    a. homogenizing allelic freqs
  32. IV. Mutation

    Mutation occurs a)_______. Therefore,
    b)______ of the Hardy-Weinberg model is almost certain to be violated
    a. constantly

    b. first assumption
  33. Effects of Mutation

    I. Constantly a)____ into all pops at all loci.
    o b) Increases_______ in pops
    o Random with respect to c)_____.
    a. introduces new alleles

    b. genetic diversity

    c. fitness
  34. True or false

    Is mutation an important cause of evolutionary change?
  35. Mutation a)______ often enough
    a. does not occur
  36. Most mutations give rise to a)_____ that decrease b)_____.
    a. deleterious alleles

    b. fitness
  37. Mutation as an Evolutionary Mechanism

    Mutations happen a)____ to cause dramatic changes in b)______.
    a. too infrequently

    b. allele frequencies
  38. Mutation is an a)______mechanism compared with selection, genetic drift, and gene flow.
    a. extremely slow
  39. Mutation can play a role in a)____when the number of alleles is b)_____.
    a. evolution

    b. high
  40. Mutation introduces a)______ into every individual in a population every generation
    a. new alleles
  41. In sexually reproducing organisms,
    a)_____ generates new combinations of alleles as well. Therefore, mutation restores b)_______.
    a. genetic recombination

    b. genetic diversity
  42. What role does mutation play in evolutionary change?

    Mutation was the a)______ in these populations.
    a. only source of genetic variation
  43. The role of mutation in evolutionary change.

    Competition experiments proved that
    a)______ dramatically over time.
    a. relative fitness increased
  44. True or false.

    Is mutation the ultimate source of genetic variability?
  45. Without mutation, there is no a)_____ on which b)______ can work.
    a. genetic variability

    b. natural selection
  46. Although mutation rates are a)___for individual loci it may be high throughout entire b)_____.
    a. low

    b. genomes
  47. Mutation becomes an evolutionary force when
     Considered a)_____entire genomes
     Combined with b)_____.
    a. across

    b. Combined
  48. Nonrandom Mating

    Inbreeding is a)______between b.______.
    a. nonrandom mating

    b. relatives
  49. Inbreeding depression: loss of
    a)____that takes place when b)_____.
    a. fitness

    b. homozygosity increases
  50. Inbreeding depression occurs because the freq of a)_______ recessive alleles b)_____.
    a. detrimental homozygous

    b. increases
  51. Does inbreeding cause evolution directly?
  52. No
  53. Inbreeding a)____ change allele frequencies
    a. does not
  54. Inbreeding can speed the rate of a)____.
    a. evolutionary change