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Chapter 17: Population Genetics and Evolution (Evolution and the Origin of…

- - - - sides of a road cut
      - recently burned area
      - recently flooded area covered with rich sediments
  - - - conditions
        
        more offspring produced than can be supported
        
        progeny must differ from each other in their alleles
      - most significant in gene pool changes
      - survival of the fittest
      - can only act on preexisting alleles
      - does not cause mutations
    - - intention
      - planning
      - purpose
      - voluntary decision making
    - - humans change frequency of gene pool
      - examples
        
        selective breeding of crops
        
        selective breeding of animals
      - carried out in conjunction with artificial mutation
    - - organisms cannot adapt to these
      - examples
        
        volcanic eruption produces poisonous gas
        
        floods
        
        droughts
        
        molten rock destroying everything in an area
      - can be small or large
    - - existing alleles decrease in frequency
      - new alleles increase
- - - - cacti and euphorbias
  - - - pollen transfer
        
        carry one haploid genome
        
        all alleles are present in its pollen grains
        
        wind distributed pollen
        
        ragweed
        
        grasses
        
        conifers
        
        animal-mediated pollenation
        
        contributes to gene flow
      - vegetative propagation
        
        small mobile pieces
        
        reproduce vegatatively
        
        various alleles come together by gene flow
      - seed dispersal
        
        long-distance dispersal
        
        migratory animals can disperse seeds
        
        caused by wind, flooding, and stream flow
    - - abiological reproductive barriers
        
        physical, nonliving feature
        
        prevents two populations from exchanging genes
        
        geographic speciation
        
        allopatric
        
        when speciation results
        
        example
        
        mountain ranges
      - biological reproductive barriers
        
        prevents successful gene flow
        
        differences in flower, color, shape, or fragrance
        
        sympatric speciation
        
        two groups become reproductively isolated
        
        grow together
        
        example
        
        monkey flower; Mimulus lewisii
      - adaptive radiation
        
        special case of divergent evolution
        
        species rapidly diverges into new species
        
        founder individuals
        
        initial gene pool is extremely small
        
        genetic drift #
        
        can occur in mainland populations
- - - - formation of seaside pools at high tide
      - absorption by clay particles
  - - - formed at random
      - controlled only by relative solubility
      - not postulated
  - - - contain organic compounds
      - contain amino acids
    - - contain alcohols, sugars, amino acids, nitrogenous bases
  - - - present in a virtually all organisms
    - - may have absorbed ATP
      - generated ATP by fermentation with glycolysis
  - - - UV and radiation
      - heat
      - electricity
      - volcanoes
      - rainstorms
    - - chemosynthetic life
        
        had basically no time limits
        
        lack of free molecular oxygen
    - - second atmosphere
        
        produced by released gases from rock matrix
        
        replaced first atmosphere that was lost in space
        
        meteorites
        
        produced
        
        methane
        
        hydrogen sulfide
        
        ammonia
        
        water
      - reducing atmosphere
        
        early second atmosphere
        
        lack of molecular oxygen
        
        powerful reducing agents
  - - - allowed the world to rust
        
        lowered concentration of free oxygen
      - allowed for aerobic respiration
    - - derived from early second atmosphere
      - addition of oxygen from photosynthesis