aBio Evolution

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Author:
tjtolman
ID:
147586
Filename:
aBio Evolution
Updated:
2012-04-22 10:56:20
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Bio
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EVOLUTION
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  1. Charles Darwin
    • 1809-1882 British
    • 1831- Done w theology school
    • Naturalist on HMS Beagle 1831-1836 (5 years)
    • Galapagos islands (off pacific s america) 6 weeks
    • -Saw: toroises, mocking birds, finches, cacti, etc...
    • Came home- thought/writing/reading/communication
  2. Thomas malthus
    • 1798 Essay
    • Charles lyell 1830 geology (earth is old)
  3. 1842
    • Essay of 1842
    • Not published
  4. 1858
    • Got a letter from naturalist Alfred Russell Wallace
    • July 1st 1858 - joint papers given by wallace and by darwin
  5. 1859
    • Published "origin of species"
    • Ideas- world is not static, it is changing
    • Change could be spoken as "evolving"
    • Evolution is "Gradual"
    • Natural selection is a process / results in evolution
  6. Phenotype / Genotype:
    Physical characteristics
  7. Population:
    Group of organism, interbreeding, in 1 area, in 1 species
  8. Gene pool
    at the genes in a population
  9. Environment:
    • biotic factors - Living
    • abiotic factors - non living
  10. variation:
    mutation
  11. Natural Selection -
    • Differential perpetuation (survivial/reprodcution) of genotypes
    • (some genotypes do better than others)
    • 1. organisms can reproduce sexually
    • 2. there is inheritable variation
    • 3. testing of organisms by environment
  12. EXAMPLE OF NATURAL SELECTION:
    • Gophers: digging abilities
    • F: faster
    • f: slow
    • FF Ff ff
    • Foxes eat ff --> FF Ff
    • Example of natural selection - some genotypes have done better than others.

    • Allele freq: Before: F 3/6 f 3/6
    • After: F 3/4 f 1/4
  13. Change in allele frequencies:
    • "microevolution"
    • Natural Selection is a process and results in microevolution
  14. Types of NS: stabilizing NS
    • 1. Stabilizing N.S.
    • Example: human birth weight
    • Those on ends of curve are at a disadvantage
  15. Directional NS
    • individuals at one end of the curve are at an advantage at other end they are at a disadvantage.
    • Ex: squirrels w longer fur survive through winter
    • Ex: increased resistance to antibiotics in bacteria
    • Ex: Plants around mine tailings
    • Ex: moth coloration: Melanistic moths *industrial melanism)
    • Pre 1850- moths were light, mostly
    • Post 1850- many moths are dark
  16. Disruptive NS:
    both Ends of curve are at an advantage (bird beaks)
  17. Adaptation:
    • Any function or structure that produces better adjustment of organism to environment.
    • Natural selection (process)---> adaptation
  18. Microevolution:
    • Change in allele frequencies through time
    • (NS) process ----> microevolution
  19. CoEvolution:
    2 or more species interacting, and they are selective force on other. (deer and wolves)
  20. Variabiltiy-
    • IT EXISTS-
    • 1. origin - mutation
    • 2. How is it observed / quantified?
    • a) morphological variation (ex flower color)
    • b) enzyme variabilty -
    • allozymes- alternate forms of an enzyme
    • -coded for by same locus
    • -gel electrophoresis may tell them apart
    • H: heterozygosity - % loci heterozygous in an individual (humans 7%)
    • P: polymorphism - % loci polymorphic in an population (humans 38%)

    • c) variation in DNA - more vairabilty in dna than in enzymes.
    • aa - diff codons --- variability

    • d) eq of variabilty - hemoglobin molecule (sickle cell anmenia)
    • Higher in africa - carrier for sickle cell - immune to malaria
  21. Fitness:
    Reproductive success
  22. H: heterozygous %

    P: polymorphism %
    percent heterozygous (humans 7%)

    percent polymorphic (humans 38%)
  23. Arguments for variability:
    • Degeneracy of genetic code
    • Traits like ABO blood types
    • Allozyme studies
    • Recent DNA sequencing work
  24. Degeneracy of genetic code:
    • same a.a. --- codon 1, codon 2, codon 3
    • variabilty in codons
  25. Allozyme studies:
    • some studies, diff allozymes are found more in diff. environments.
    • Barheaded goose- hemolains - high evelation
    • Andean goose - andes - high elevation
    • Both have allozymes of hemoglobin that carry O2 better.
  26. Recent DNA sequencing work:
    • a) enzyme
    • active site: less variability
    • away from active site: more variabilty
    • b) much dna is non-coding (more variabilty)
    • A little dna codes for protein (less variabilty)
  27. Neutral Theory:
    • Better---->Mutation----->Worse
    • +------> neutral(most)------> -
    • Alleles neutral
  28. Allele frequencies:
    • studied at POPULATION geneticits
    • Look @ allele freq and genotype freq. (mathematical)
  29. Microevolution:
    • Change in allele freq.
    • -Diff. agents/forces that can change allele freq.
    • ex) natural selection
  30. Basic assumptions / Starting point for allele freq:
    • Hardy Weingberg Equilibrium:
    • Diploid organisms
    • meiosis
    • random mating = panmixia
    • assume no mutation, no NS, no immigration
    • population is large
  31. Weinberg assumptions:
    • 1) no mutation
    • 2) no immigration
    • 3) random mating
    • 4) pop. siz is large
    • 5) No NS
  32. Hardy weinberg equilibrium:
    • If above assumptions are true, then distripution of genotype and allele freq stay constant.
    • IF NO CHANGE = NO CHANGE
  33. Locus with alleles A and a
    • Genotype: AA, Aa, aa
    • Number of AA individuals: N(AA)
    • Total pop. size: N
    • Freq of AA:. f(AA)
  34. Total number of alleles in population: 2N alleles
    • f(A) = p
    • f(a) = q

    p= 2N(AA) + N(Aa) / 2N

    q= 2N(aa) + N(Aa) / 2N
  35. Freq. of AA =
    f(AA) = N(AA) / N
  36. Calculate genotype freq. and allele freq.
    500 people
    405AA
    90Aa
    5aa
    • Genotype: AA: 405/500
    • Aa: 90/500
    • aa: 5/500
  37. Example: PTC = T, t
    TT Tt tt (nontaster)
    american causasians: 70% tasters
    30% non tasters
    What is genotype and allele freq.
    • f(TT) = p x p = p^2
    • f(Tt) = 2pq
    • f(tt) = q x q = p^2

    • Given: f(aa) = .3 = q^2 --> square root of .3 = .55
    • allele freq: f(T) = 1-.55 = .45

    • Genotype freq:
    • f(TT) = p^2 - .45^2 = .202
    • f(Tt) = 2pq = .495
    • f(tt) = .3
  38. Hardy weinberg equilibrium assumed:
    Relax the hardy weinberg assumptions:
    • 1) mutations exist (origin of variation)
    • (low rates 10^-4 to 10^-6 mutations/locus/generation)
  39. How important is mutation in changed allele freq?
    • A <-----> a
    • u= "mu" rate of mutation --->
    • v= "nu" rate of mutation <----
  40. Say u= 10^-5 and v= 10^-4
    A<---->a

    A<----a-mutation is bigger
  41. equilibrium vale of p:
    • p = v / u+v
    • p = .91 = f(a) ----50,000 generations to get to equilibrium
    • Mutation is not a strong force in changing allele freq.
  42. For NS to occur and evolution:
    • -variation among individuals in a pop.
    • -result in diff # of offspring
    • - variation must be genetically inherited
  43. Large pop. size assumptions:
    • "genetic drift" - change in allele freq. due to change
    • ex: founder effect -small group of organisms found a population.
    • ex: bottle neck effect -disaster, pop. size gets small
  44. Macroevolution:
    Evolution change at and above species level
  45. species: concepts of species
    • a) Morphology (morphological concept) form "looks like" "good morphological species"
    • (botonists)
    • b) Biological species concept- interbreeding ability (cant use in fossils)
  46. Speciation:
    production of species
  47. One kind os speciation:
    • involves geographic isolation
    • 2 populations - slightly diff. gene pools
    • experience diff mutations
    • experience selection pressures (NS)
    • 2 diff pop ---> 2 diff species
  48. Adaptive radiation:
    • production of several species
    • ex: galapagos finches
  49. If two diff groups met again what happens?
    • REPRODUCE OR STAY ISOLATED (DO NOT REPRODUCE)
    • Depends on reproductive isolating mechanisms- have they evolved?
  50. Properties of organisms which prevent interbreeding
    • 1.) ecological RIM (reproductive isolating mechanism)
    • -potential mates do not meet
    • 2.) Temporal RIM-
    • 2 groups reproduce @ diff. times
    • insects / amphibians / plants
  51. Teology:
    philisophical - final causes exist in nature
  52. 5 agents of evolutionary change:
    • mutation
    • gene flow
    • non random mating
    • genetic drift
    • selection

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