Evolution 2

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Evolution 2
2010-02-20 15:21:27
mutation adaptation hardy weinberg

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  1. Adaptation
    -heritable trait taht increases the fitness of an individual in a particular environment relative to those lacking the trait
  2. Natural Selection
    • -ends with adaptation
    • -NOT physiological (ex. warm weather, different genes turned on)

    • Precondition:
    • 1. must be a heritable variation in a population
  3. Modern Synthesis
    • -1930-1940
    • -argued that population processes (mutation, recombination, natural selection) account for the orgin of species
  4. Darwinian Evolution
    • -change in genetic makeup of a poptulation over time
    • -driven by natural selection
  5. Mutation
    • -Incorrect replication: spontaneous
    • -Chemical/radiation mutations: induced
  6. Mutation on DNA
    • -mismatching DNA pairs.
    • -proof reading andr repair enzymes help
    • -not mutation until its stuck forever

    • ex. substitution (transition-similar, transverson)
    • -frameshift (deletion, insertion)
    • -inversion (flipping 180)
    • -reciprocal translocatoin (break DNA and reinsert somewhere else)

    • nonsynonymous: change
    • synonymous: no change
  7. mutation rate and natural selection
    • -mutation in repair enzymes cause 100-1000x higer mutation rate
    • -high mutation rate under changed conditions can be an advantage
  8. mutations on fitness
    • -most lead to death
    • -deleterious- incorrect protein, no protein, homeotic mutations
    • -reduce by 2%
    • -neurtral mutations- no effect on fitness, silent
    • -positive
    • -rare (ex. mutate to grow better at different conditions)
  9. obtaining new genes
    -unequal crossing over
    -transposable elements
    -gene duplications
    -chromosome mutations
    -genome duplication
    • -unequal crossing over: prophase, meiosis 1- lose gene
    • -transposable elements: jumping genes
    • -gene duplications: only need 1 to do function, other can mutate
    • -chromosome mutations: inversion (ABCDE to ABEDC)
    • -good evidence for natrual selection
    • -genome duplication: may create new species, masive gene duplication
  10. mutation random
    -respect to selective advantage
    -respect to postion in genome
    • selective advantage
    • -yes, mutations do NOT occur due to need
    • postion
    • -no, mutational hot spots (due to unusual character)
  11. gene pool
    • -total of all the alleles of a gene that occur in a population
    • -same species = same genes
    • -the alleles of these genes may vary
  12. phenotypic variation
    • environment causes change in phenotype
    • -ex coloring
  13. Hardy Weinberg
    -conditions on which a population will NOT evolve

    -within popluations (group of interbreeding individuals and thier offspring)

    • -large populations with random mating, allele frequences remain constant
    • -allele: p +q = 1
    • -genotype: p2 +2pq + q2 = 1

    • Population NOT to evolve:
    • -no mutation
    • -no migration
    • -no natural selection
    • -large population size
    • -random mating
  14. Population genetic structure can change by
    • -mutation
    • -migration
    • -natural selection: certain genotypes produce more offspring, causes divergence, leads to adaptation
    • -genetic drift: due to chance alone
    • -non random mating: interbreeding cause heterozygous to disapper and homo to appear
  15. genetic drift
    -founder effect
    • -isolated colonies are founded by a small number of individuals
    • -allele frequences may be different than large group
  16. variation amount popluations of same species
    • sympatric: populations overlap in distribution
    • parapatric: adjacent populations
    • allopatric: populations w/ isolated distributions
  17. clinal variation
    change in character or allele frequencies over geographic distance
  18. fixed difference
    on population having an allele and not the other popluation