Microevolution and Macroevolution

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Microevolution and Macroevolution
2010-11-02 16:00:02
biology evolution midterm2 bsci207

Microevolution and Macroevolution
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  1. Four Mechanisms of Microevolution
    • 1. Mutation- addtion of new alleles to a population through changes in DNA
    • 2. Immigration- introduction of new allele or additional copies of existing alleles via members of different populations
    • 3. Genetic Drift- changes in frequency of alleles in a population due to random effects
    • 4. Selection- changed in frequency of alleles in a population due to differential survival and reproductive sucess of individuals carrying specific alleles
  2. Euridian
    Element that has a great inifinity to to bind to iron, usually comes from surface of extraterrestial sources- indicating major impact event
  3. Mass Extinction
    (Principle of Hierarchial View)
    • 5 major mass extinctions have played a significatn role in shaping modern diversity
    • ex. KT extinction

    • Bolide impact events
    • Flood Basal Eruptions- Volcanism
    • Eustatic sea-level changes- changing sea level due to Plate tectonics and climate change <-- buggest mechanism for evolution
  4. Faunal Turnover
    (Principle of Hierarchial View)
    Comparision of clade diversification can reveal major events in the history of life

    • representatives from 3 statistically distinct "Faunal Cohorts" showing patterns of diversification:
    • 1. Vendian-Cambrian Fauna
    • 2. Cambrian-Palaeozoic Fauna
    • 3. Mesozoic-Cenozoic Fauna
  5. Gambler's Ruin Model
    (Principle of Hierarchial View)
    • Orgin and extinction of clades can be modeled as a random process
    • repeates many times before the "gambler losses"--> total extinction
  6. Hierachical model of Macroevolution
    Patterns of orgin, diversification & extinction of clades can reveal major events in the history of life

    • arises through unique, large-scale phenomena
    • contingent historical events are important-especially random
    • e.g. KT extinction
  7. Extrapolationist model of Macroevolution
    Accummulated effects of microevolution over very long periods of time

    • no unique phenomena
    • extinction
    • evolution is continous adaptations
    • e.g. horse
  8. Macroevolution
    Broad scale patterns of change above species level over geological time. Historical contingency determines which lineages persist.

    • Cladogenesis(speciation) is the main creative process
    • Extinction (lineage sorting) is the main destructive process
  9. Microevolution
    Genetic changed within a population level over ecological time scales; selection determines which traits persist.

    • Mutation is the main creative process
    • Selection is the main destructive process