Bio Final 3

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  1. 2 Major Features of Most Genetic Traits
    • 1. Complexity of the genotype-phenotype relationship-no single factor is both necessary and sufficient to cause a phenotype, causes of variation of a phenotype does not equal cause of a phenotype
    • 2. Confoundment of frequency and apparent causation in complex systems-requires population studies
  2. 5 Observations 3 Inferences of Natural Selection
    • Obv1. Organisms have great potential fertility, permiting exponential growth of populations
    • Obv2. Natural populations remain fairly constant in size, not increasing exponentially
    • Obv3. Natural resources are limited
    • Inf1. A struggle for existence occurs in a population
    • Obv4. Variation occurs among organisms within a population
    • Obv5. Variation is heritable
    • Inf2. Varying organisms show differential survival and reproduction, favoring advantageous traits-natural selection
    • Inf3. Natural selection over many generations gradually produces new adaptations and species
  3. Abstraction and Simplification
    identify essential aspects of reality and remove distracting elements
  4. Adaptation
    a trait that evolved by natural selection for a particular biological role
  5. Additive Genetic Variance
  6. Additive Genotypic Deviation
    gai=sum of avg. excess of all phenotypes involved
  7. Additive Variance v. Non-Additive Variance
    how much of the genetic variance can be transmitted to influence the phenotypic variation in the next generation
  8. Algorithm
    • 1. Substrate nutrality-reproducting population with heredity and variation
    • 2. Underlying mindlessness
    • 3. Guranteed results
  9. Assumptions
    unreal conditions used to facilitate study eg non-overlap generations, infinite population
  10. Average Excess
    avg. excess=Σ(freqallele)(gi)
  11. Biological Species Concept
    Mayr-A reproductive community of populations (reproductively isolated from others) that occupies a specific niche in nature
  12. Broad-Sense Heritability
  13. BSC Problems
    • 1. sexual forms only
    • 2. no temporal dimension-BSC is for a slice of time and does not show lineage through time
    • 3. not a single unit of evolution-divergence of character does not equal different species
    • 4. not practically testable-sexual behavior in lab doesn't always reflect behavior in habitat
  14. Characteristics of Math Models
    • 1. Abstraction and Simplification
    • 2. Sufficient Paramaters
    • 3. Assumptions
  15. Coalescence
    all copies of homologous DNA trace back to a common ancestral molecule
  16. Codominant
    both phenotypes observed when heterozygous eg sickle cell electrophoretic mobility
  17. Correlation Coefficient Between Parent and Offspring
  18. Correlation Coefficient Between Siblings
  19. Correlation Coefficient
    • Between X and Y
    • =[Cov(X,Y)]/[sqrt(σx2σy2)]
  20. Covariance
    • between X and Y
    • Avg(X-µx)(Y-µy)
  21. Deme
    a local population of reproducing individuals that has physical continuity over time and space, lowest biological level that can evolve
  22. Dietary Disease (v. genetic disease)
    diet is the rarer factor of the disease and the genetics is common
  23. Dominance Variance
    • same as non-additive genetic variance in a single locus model
    • σd2g2a2 (single locus model)
  24. Dominant
    presence of one allele masks the phenotype of the other eg sickle cell malarial resistance
  25. Environmental Interactions
    Phenotype affected by non-genetic forces, which may include other phenotypes within the body eg LDL cholesterol level
  26. Epistatic Variance
    • part of non-additive variance in population level arising from inheritance among genotypes at different loci
    • when comparing two populations, the rarer genotype shows more additive variance when epistatically correlated
  27. Evolution
    change in allele/gamete frequency in gene pool, fates of alternate forms of genes over space and time ina population
  28. Evolutionary Forces in Populations
    Mutation and Genetic Drift
  29. Exaptation
    a trait coopted by natural selection for a role incidental to the trait's origin
  30. Fisher's Analysis of Variance
  31. Founder Event
    rare dispersal across pre existing barrier eg Galapagos
  32. Gene Pool
    the population of gene copies and potential gametes collectively shared by individuals of a deme
  33. Gene Tree
    branches show lineal descent of copies of homologous DNA
  34. Genetic Disease (v. dietary disease)
    genetics is the rarer factor of the disease and the diet is common
  35. Genetic Drift
    random changes in allele frequency due to finite number of population size (sampling error), directionless, cumulative, strength is inversely proportional to 1/(2N), rate of losing allele =1/(2N), avgerage time for two genes to coalesce=2N, avgerage time for all genes to coalesce=4N
  36. Genetic Variance v. Environmental Variance
    how much phenotypic variance is associated with genotypic variation in a population in a given generation
  37. Genetic Variance
  38. Genome Scan
    SNP markers every 10 cM in genome of population, which must have high frequency of phenotype and high linkage disequilibrium
  39. Genotypic Deviation
    gi= -x-pog--x-pop
  40. Gradualism
    less empirical support accumulation of small, quantitative changes leads to qualitative change
  41. Haplotype Tree
    branches denote mutational events in the evolutionary histroy of homologous DNA
  42. Haplotype
    Set of identical haploid genomes for a specified unit of measurement (same as allele for measurements taken at DNA/chromosomal level) In common usage-bases present at polymorphic sites genotypically linked on a DNA molecule eg SNPs RFLPs
  43. Hopeful Monster
    large phenotypic change in a single generation eg Ancon sheep
  44. Identify by Descent
    replication without mutation, refering to alleles and associated phenotypes eg mitochondrial DNA
  45. Mean
    • µ (or -x- for a sample population)
    • (x1+x2+...+xn)/n
  46. Mendelian Epistasis
    not sufficient for epistatic variance at population level
  47. Molecular Basis of Evolution
    DNA can replicate, can mutate and recombine, encodes RNA/proteins that interact with environmental conditions to influence a phenotype
  48. Mutation Rate
    • µ unitless
    • # newly mutated copies
    • total # copies of homologous DNA
  49. Mutation-Selection Equilibrium
    mutation produced lethal alleles and selection removes them
  50. Mutation
    causes many small changes
  51. Narrow-Sense Heritability
  52. Natural Selection
    • a population based mechanism of evolutionary change invoked to explain adaptation
    • Not a random process
    • Random component-variation is produced at random with respect to organism's needs
    • Non-random component-organisms with favorable traits have higher rates of survival and reproduction, causing populations to accumulate the most favorable variants and discard less favorable ones
  53. Non-Additive Genetic Variance
    • 1. Single locus model=σd2
    • 2. Multilocus model=σd2epistatic2
  54. Non-Allopatric Speciation
    Larson disagrees geographic isolation does not precede evolution of species
  55. Norm of Reaction
    set of phenotypes associated witha particular genotype in interacton with a variety of environmental conditions and genetic backgrounds
  56. Overdominant
    heterozygote phenotype is more fit than phenotype of either homozygote eg sickle cell heterozygote viability in malarial environment
  57. Parent-Offspring Covariance
    measures heritability without measuring genotype
  58. Phenotype
    any measurable trait, either discrete or continuous
  59. Phylogenetic Species Concept
    Carcraft-A lineage of ancestor-descendant populations diagnosably distinct by divergence of character
  60. Pioneer Fund
    Hate group that wants to prove that black people are genetically inferior
  61. Polygenic
    Ronald Fisher-multiple loci contribute to the phenotype
  62. Postzygotic Reproductive Barriers
    hybrid invariability, hybrid sterility, hybrid breakdown
  63. Prezygotic Reproductive Barriers
    temporal, ecological, behavioral, mechanical, gametic
  64. Progressive Adaptation
    later forms are superior to early ones in a general sense
  65. Quantitative Genetics
    analysis of genetic variance for continuously varying phenotypes within a population
  66. Quantitative Trait Locus (QTL)
    • locus whose variation contributes to population variation of a continuously varying phenotype
    • found using genome scan followed by tree scan
  67. Randomness
    mutations can be good or bad
  68. Recessive
    phenotype only observed when homozygous eg sickle cell severe anemia
  69. Reinforcement
    controversial selection on hybrids with postzygotic barriers leads to prezygotic barriers
  70. Single Gene Inheritance
    Phenotype is the result of only one locus
  71. Sources of Allopatry
    vicariance and founder event
  72. Sufficient Parameters
    minimum mumber of summary variables, combining relevent information of many parameters at lower levels eg "fitness"
  73. Sympatric Speciation
    multiple species lineages generated from an ancestor in an undivided geographic area
  74. Tree Scan
    • haplotype tree used to test SNP sites for influence on the phenotype
    • group all haplotypes on either side of a particular branch, call them A1 and A2, measure norms of reaction for the resulting genotypes A1A1, A1A2, A2A2, repeat for all branches in tree
  75. Variance
    • σ2 (or s2 for a sample population)
    • σ2=[(x1-µ)2+(x2-µ)2+...+(xn-µ)2]/n
    • s2=[(x1--x-)2+(x2--x-)2+...+(xn--x-)2]/(n-1)
  76. Vicariance
    subdivide formerly continuous habitat
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Bio Final 3
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