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Chapter 17 Population Genetics and Evolution (Rates of Evolution (most…

- - - - another new species
      - several new species
    - - natural selection
        
        mutations occur
        
        causes new
        
        alleles
        
        genes
        
        may cause it to be
        
        less adapted
        
        to their environment
        
        more adapted
    - - can take millions of years
        
        to change species
  - - - deleterious
        
        hard to reproduce
      - beneficial
        
        more likely to reproduce
  - - - Charles Darwin
      - Alfred Russel Wallace
    - - survival of the fittest
- - - - all genomes
        
        subjected to
        
        mutagenic factors
        
        mutations
      - existing alleles
        
        decrease in frequency
      - new alleles
        
        increase
    - - events where organism
        
        cannot adapt
        
        examples
        
        meteorite hits Earth
        
        eliminates all life in region
        
        organisms and alleles lost
        
        1 more item...
        
        volcanic eruption
        
        Infrequent
        
        floods
        
        small plants susceptible
        
        1 more item...
        
        droughts
        
        hailstorms
    - - humans purposefully change
        
        allele frequency
        
        such as
        
        using selective breeding
        
        humans do this to
        
        increase protein quality
        
        increase survivability
        
        increase flower abundance
      - carried out in conjunction
        
        with artificial mutation
        
        plants exposed to mutagens
        
        increase number of new alleles
    - - most significant factor
        
        causing gene pool changes
      - described as
        
        survival of the fittest
      - two conditions must be met
        
        must produce more offspring
        
        than can possibly grow
        
        survive to maturity
        
        influenced by
        
        limited resources
        
        predators
        
        pathogens
        
        competition
        
        for
        
        3 more items...
        
        progeny must differ from
        
        each other in
        
        their types of alleles
        
        if similar then
        
        will be affected by
        
        1 more item...
    - - Includes
        
        purpose
        
        intention
        
        planning
        
        voluntary decision making
      - Situations in which Natural Selection Does Not Operate
        
        Cannot operate if
        
        all individuals similar genetically
        
        impossibility to adapt to condition
        
        survival is universal
      - Multiple Selection Process
        
        Loss of individuals and
        
        reduced reproduction
        
        not caused by single factor
        
        new advantage allele
        
        may be lost
        
        due to phenomenon
        
        that plant is not
        
        resistant to
        
        could survive
        
        and improve species
        
        frequency remain low until
        
        allele is needed
        
        could be disadvantage
        
        if
        
        allele is not needed
        
        depends on environment
- - - - examples
        
        lycopods
        
        ferns
  - - - aster seed
        
        new specie arises
        
        every 500,000 years
  - - - such as
        
        flowers
        
        leaves
        
        fruits
        
        shoots
        
        trichomes
- - - - two fundamental ways
        
        phyletic speciation
        
        where one species gradually
        
        so changed it
        
        is considered new species
        
        divergent speciation
        
        where some of a population
        
        evolve into
        
        new second species
  - - - if new allele is
        
        carried by wind then
        
        it can travel great distances
      - Animal-mediated pollination
        
        also contributes with gene flow
        
        usually covers small area
        
        allele movement is rapid
    - - Seeds and fruits
        
        fall close to parents
        
        but can be carried by
        
        floods
        
        wind
        
        stream flow
        
        to islands by
        
        rafting
        
        can be spiny
        
        or gummy
        
        helps stick to
        
        fur and feathers
        
        helps spread to great distances
    - - small, mobile species
        
        that reproduce vegetatively
        
        contribute to gene flow
      - if various mechanisms are efficient
        
        species remain relatively homogeneous
  - - - any physical, nonliving feature
        
        that prevents two populations
        
        from exchanging genes
      - original species
        
        physically divided into
        
        two or more populations
        
        cannot interbreed
        
        if speciation results
        
        called allopatric
        
        1 more item...
      - Reproductive barriers
        
        entire mountain ranges
        
        prevents spread of pollen
        
        rivers
        
        usually for small animals
        
        rarely prevent
        
        plant gene flow
        
        by means of seed dispersal
    - - any biological phenomenon
        
        that prevents
        
        successful gene flow
      - Sympatric speciation
        
        two groups become
        
        reproductively isolated
        
        even though they grow together
      - Effective barriers
        
        if species is pollinated by
        
        discriminating pollinator
        
        certain gene will not
        
        reproduce enough to
        
        stay alive
        
        Evolutionary Changes in pollinators
        
        range of plants may affect
        
        variations of environment
        
        which can lead to
        
        differing evolutions for animals
        
        prezygotic isolation mechanisms
      - Postzygotic internal isolation barriers
        
        plant divergence comes from
        
        environmental diversity of
        
        large geographic range
        
        earliest form
        
        hybrid sterility
        
        two populations occasionally
        
        interbreed or
        
        artificially cross pollinated
        
        2 more items...
  - - - into many new species
        
        over extremely short time
    - - first, founder individuals
        
        initial gene pool extremely small
        
        if one seed is founder
        
        original gene pool consists of
        
        two sets of alleles
      - gene pool changes rapidly
        
        more subject to accidents
    - - Species habitat with
        
        little or no competition