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Chapter 18 Mind Map, Crossing Over, Identicle Plants, Prezygotic Barrier,…

- - - - pollen transfer is when pollen is moved by wind, animal, or other
      - seed dispersal is when seeds are moved by wind, animal, or other
      - vegetative propagation is when mobile pieces that hold alleles are moved to other places
  - - - abiological reproductive barriers are physical, nonliving, diving features
      - biological reproductive barriers are phenomenon that prevent gene flow
      - when two groups remain reproductively isolated, even when they are close together, it is called sympatric speciation
  - - - act before a zygote can be formed
      - barriers which prevent pollination or fertilization
    - - barriers prevent subpopulational breeding due to differences in genome
      - two subpopulations must be considered different species
    - - one of the earliest postzygotic barriers
      - occasional cross-pollination which produces a sterile
      - happens between two close populations
    - - occasional cross-pollination produces an zygote which dies early in its development
      - happens between two close populations
  - - - all offspring from founder resemble the founder (founder individuals)
      - if one seed is founder, gene pool has two alleles
- - - - first atmosphere consisted mostly of hydrogen
      - second atmosphere
        
        contained mostly H2S, NH3, and CH4
        
        released by gases from rocks and meteorites
        
        molecular oxygen was absent
        
        was a reducing atmosphere
    - - highly reactive free radicals (due to gamma and UV rays)
      - heat
      - electricity
      - lightning (from volcanoes)
    - - no limits for chemosynthetic origin of life
- - - - genomes are subjected to mutagens
      - mutations occur continually
      - significance of mutation depends on population size
    - - events to which an organism cannot adapt
      - many phenomena qualify as accidents
      - accidents can be small events and large events
    - - purposeful change in allele frequency of a gene pool
      - done by humans
      - purposes
        
        beneficial qualities are chosen and bred (think GMOs)
        
        production of ornamental plants (longer flowering time)
      - carried out with artificial mutation
    - - most significant factor in the change of gene pools
      - usually described as survival of the fittest
      - two conditions must be met before natural selection can happen:
        
        population must produce more offspring than environment can handle
        
        offspring must differ in their types of alleles
      - differential survival can occur if genetic diversity exists among individuals
      - competition for water and nutrients acts as a selective force
      - refers to the differential survival among organisms that have differential phenotypes
      - a population can evolve but individuals can not
      - does not always result from the action of an agent outside of the organism
    - - natural selection does not include purpose, intention, planning, or voluntary decision making