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2010-04-29 22:05:45

Evolution Test 2
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  1. transposition
    the production of copies that become inserted into new positions in the genome
  2. Kinds of mutations
    • Gene mutations (bp substitutions, point mutations, transition, transversion, frameshift mutations)
    • Recombination
    • Transposable elements --> cause changes
  3. synonymous mutations vs. nonsynonymous
    • synonymous: no efect on amino acid sequence of the protein (often in coding region)
    • Nonsynonymous: result in amino acid substitutions
  4. Intragenic Recombination
    when homologous DNA sequences differ at two or more ase pairs -- generates new gene combinations
  5. recurrent mutation
    repeated origin of a particular mutation
  6. back mutation
    mutation of a mutant allele back to the allele from which it arose (usually WT)
  7. polygenic
    the variation in most phenotypic characters is this

    based on several or many different genetic loci
  8. homeotic mutations
    redirect the development of one body segment into another (regulation of gene expression!)
  9. additive inheritance
    if heterozygotes phenotype is precisely intermediate between the homozygotes
  10. pleiotropic mutations
    affect more than one character
  11. karyotype
    description of its complement of chromosomes (number, size, shape, and internal arrangement)
  12. aneuploid
    unbalanced chromosome complement (often inviable or fails to develop properly)
  13. polyploidy
    changes in teh number of whole sets of chromosomes (more than 2 entire sets of homologous chromosomes)
  14. autopolyploids
    arisen by the union of unreduced gametes of the same species
  15. allopolyploids
    arisen by hybridization between closely related species
  16. inversion
    rearranged gene order from a loop and cross over
  17. pericentric vs paracentric
    • pericentric = inversion that includes centromere
    • paracentric = inversion that does not include centromere
  18. reciprocal translocation
    two nonhomologous chromosomes may exchange sengemnts by breakage and reunion
  19. acrocentric vs. metacentric chromosomes
    • acrocentric = centromere near one end
    • metacentric = centromere in middle
  20. fusion of chromosomes
    two nonhomologous acrocentric chromosomes undergo reciprocal translocation that they are joined into a metacentric chromosome
  21. fission of chromosomes
    metacentric with acentric??? pg. 211
  22. environmental variance
    environmentally induced variation among individuals
  23. maternal effect
    effects of a mother on her offspring not from the gnes but to nongenetic influences (yolk in egg, maternal care, physiological condition of berthing)
  24. epigenetic inhereitance
    when phenotypic differences not based on DNA sequence differences are transmitted among generations of dividing cells in multicellular organisms and also sometiems from parents to offspring (like DNA methylation)
  25. norm of reaction
    variety of different phenotypic states that can be produced by a single genotype under different environmental conditions
  26. common garden
    offspring of phenotypically different parents can be reared together in a uniform environment
  27. Hardy Weingburg Equillibrium assumptions
    • 1. mating is random (panmictic)
    • 2. population is infinitely large (no genetic drift)
    • 3. genes are not added from outside the population (no gene flow)
    • 4. genes do not mutate from one allele state to another (no mutation)
    • 5. all individuals have equal probabilities of survival and of reproduction
  28. gene glow
    mating among different populations (migration)
  29. polymorphism
    presence in a population of two or more variants (alleles or haplotypes)
  30. monomorphic
    locus/character that is not polymorphic
  31. inbreeding depression
    • inbreeding increases the proportion of homozygotes - mroe likely to get homozygote recessive (bad)
    • Therefore, decline in components of fitness (survival, fecundity)
  32. linkage disequilibrium
    association/correlation between specific allels at two loci
  33. linkage equilibrium
    no such association between specific alleles at the two loci
  34. quantitative variation
    continous/metric varaition - fits a normal distribution
  35. polygenic
    due to variation in phenotype
  36. sympatric vs. parapatric vs. allopatric
    • sympatric = if distinct populations have overlapping geogrphic dddistributions so that they occupy the same area and frequently encounter each other
    • parapatric = populations with adjacent but nonoverlapping ranges that come into contact
    • allopatric = populations with spearated distributions
  37. Bergmann's Rule
    body size increases iwth increasing latitude
  38. cline
    gradual change in a character or in allele frequencies over geogrpahic distance
  39. ecotypes
    phenotypes that are associated with a particular habitat, often in a partchy mosaic pattern
  40. random walk
    random fluctuation of alleles - p will eventually wander (drift) to either 0 or to 1 (no stabilizing force)
  41. hitchhiking
    a genotype would increase rapidly in frequency because of linkage to an advantageous mutation that had ocurred at another locus
  42. preadaptation
    feature that fortuitously serves a new function
  43. exaptations
    preadaptations that have been co-opted to serve a new function
  44. overdominant
    when the heterozygote is said to be dominant
  45. underdominant
    if heterozygote has lowest fitness
  46. Stabilizing selection
    intermediate phenotype is fittest
  47. directional selection
    if one extreme phenotype is fittest
  48. diversifying (disruptive) selection
    if two or more phenotypes are fitter than the intermediates
  49. coefficient of slection
    (s) the amount by which teh fitness of a genotype differes from teh reference genotype (1-w)

    • intensity of selection agaisnt the less fit genotype
    • selective advantage of the fitter genotype
  50. balancing selection
    selection that maintains polymorphism
  51. factors responsible for variation
    • 1. recurrent mutation producing deleterious alleles subject to weak selection
    • 2. gene flow of locally deleterious alleles from other populations in which they are favored by selection
    • 3. seletively neutrality (genetic ddrift)
    • 4. maintenance of polymorphism by natural slection
  52. antagonistic selection
    opposing forces acting on polymorphisms - usually does not maintain polymorphisms
  53. inverse frequency dependent selection
    the rarer a phenotype is in teh population the greater its fitness
  54. positive frequency dependent selection
    • the fitness of a genotype is greater the more frequent it is in the population
    • whichever allele is initally more frequent will be fixed
  55. selective sweep
    reduction/elimination of DNA sequence variation in teh vicinity of a mutation that has been fixed by natural selection relatively recently