Biology 1115 Chapter 23

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  1. Natural selection acts on the __________________, but only __________ evolve.
    • Phenotype of individuals
    • populations
  2. What is microevolution?
    is a change in allele frequencies in a population over generations
  3. What is an allele?
    alterative variation of a gene that may produce distinguishable phenotypic results
  4. What are the two process that produce genetic variation?
    • mutation
    • sexual reproduction
  5. Not all phenotypic variations are heritable, what is an example?
    big muscles
  6. Natural selection can only act on variation with a ___________.
    genetic component
  7. Define mutations.
    are changes in the nucleotide sequence of DNA.
  8. Mutations cause ________ and _______ to arise.
    • new genes
    • alleles
  9. Only mutations in cells that produce __________ can be passed to offspring
  10. What is a point mutation? (2)
    • change in one base in a gene
    • doesn't change reading frame
  11. Mutations in ____________ of DNA are often harmless.
    non-coding regions
  12. why might mutations in a gene not affect protein production?
    because of redundancy of the genetic code
  13. Mutations that result in a change in protein production can be?
    both harmful or increase the fit between organism and environment
  14. How does sexual reproduction create new combinations?
    sexual reproduction can shuffle existing alleles into new combinations
  15. What is a population?
    a localized group of individuals capable of interbreeding and producing fertile offspring
  16. What is the lowest level evolution can act on?
    a population
  17. what is a gene pool?
    consists of alleles for all loci in a population
  18. A locus is fixed if all individuals in a population are______________.
    homozygous for the same allele
  19. What does the Hardy-Weinberg Principle describe?
    it describes a population that is NOT evolving
  20. What does Hardy-Weinberg Principle state?
    states that frequencies of alleles and genotype in a population remain constant from generation to generation
  21. What is the Hardy-Weinberg equation?
    p^2 + 2pq + q^2= 1
  22. What is evolution?
    a change in genetic composition of a population from generation to generation
  23. what are the 5 conditions for non-evolving populations?
    • no mutations
    • random mating
    • no natural selection
    • extremely large population size
    • no gene flow
  24. The three factors that alter allele frequencies and bring about most evolutionary change are:
    • genetic drift
    • gene flow
    • natural selection
  25. Define genetic drift.
    describes how allele frequencies fluctuate unpredictably from one generation to the next.
  26. what is the most important thing that will help with genetic drift?
    smaller the sample/population
  27. Genetic drift tends to _________ genetic variation through losses of alleles
  28. what is the founder effect?
    occurs when a few individuals become isolated from larger population
  29. what is the bottleneck effect?
    a sudden reduction in population size due to a change in the environment.
  30. Genetic drift is significant in ______ populations.
  31. Genetic drift causes allele frequencies to change ___________.
    at random
  32. Genetic drift can lead to a ______________ within populations.
    loss of genetic variaion
  33. Genetic drift can cause harmful alleles to become ___.
  34. Define gene flow.
    consists of the movement of alleles among populations
  35. Gene flow tends to ____________ between populations over time.
    reduce differences
  36. Gene flow is more likely than mutation to ______________.
    directly alter allele frequencies
  37. Gene flow may either ___________ or ________ the fitness of a population.
    decrease or increase
  38. Define natural selection.
    differential success in reproduction results in certain alleles being passed to the next generation in greater proportions
  39. natural selection brings about adaptive evolution by acting on an organism's _______.
  40. Only natural selection consistently results in ____________.
    adaptive evolution
  41. What mode of selection does directional selection favour?
    favours individuals at one end or the other of the phenotypic range
  42. What mode of selection does disruptive selection favour?
    favours both extremes of the phenotypic range
  43. What mode of selection does stabilizing selection favour?
    favour intermediate variants and acts against extreme phenotypes
Card Set
Biology 1115 Chapter 23
The evolution of populations
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