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Review organic evolution


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Quick review of concepts of organic evolution

Quick review of concepts of organic evolution

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  • 1. A Quick Review ofEvolution
  • 2. Evolution
    Evolution is the central theme of biology
    Nothing in biology makes sense except in the light of evolution
    Theodosius Dobzhansky
  • 3. Evolution
    Evolution: change over time; can be applied to many things, so we use a more specific definition in biology
    Organic evolution = change in allele frequencies over time
    Allele = alternate form of a gene; if one variation of a gene confers some sort of advantage in a particular environment, it is more likely to be passed on.
  • 4. Evolution
    The term evolution does not imply a mechanism
    many mechanisms have been hypothesized
    Natural Selection is accepted as the primary mechanism of adaptive evolution
    Other mechanisms include sexual selection, genetic drift, and genetic bottlenecks.
    How does evolution occur?
  • 5. Speciation
    Speciation: the formation of a new species
    can proceed by many mechanisms
    results in the bifurcation(separation of 1 into 2) of a lineage(group of related organisms)
  • 6. Speciation
    Allopatric Speciation: believed the most common method of speciation (and the method of human speciation).
    Results primarily from genetic drift and Natural selection
  • 7. Genetic Drift
    Genetic Drift: random change in allele frequencies over time
    most common in genes not subject to natural selection
    Differences accumulate when two populations become separated from each other.
  • 8. History of Evolution
    Evolution is an old theory
    Darwin didn’t come up with evolution
    He did provide evidence for it and therefore popularized it and made possible the scientific discipline called evolutionary biology.
    He also didn’t come up with the phrase “survival of the fittest” that you should probably forget you ever heard.
  • 9. Darwin
    Charles Darwin used and preferred the phrasedescent with modification
    Darwin developed the theory of Natural Selection
    It is a mechanism of evolution, not an equivalent term to evolution
    Who came up with the idea of natural selection independent of Darwin?
    Alfred RusselWallace
    Known as the father of biogeography
  • 10. Influences
    Charles Lyell
    Popularized uniformitarianism, a concept developed by James Hutton.
    Thomas Malthus
    Wrote an essay on population that highlighted a struggle for limited resources in a large population.
  • 11. Inspiration - Geology
    Uniformitarianism:the processes which shape the earth today are the sameandoccur at the same ratesas the processes that have shaped the earth in the past
    For example, canyons formed over a very long time through the same process of erosion as occurs right now; sand on the beach formed through millenia of waves hitting the shore just like they do now.
  • 12. Natural Selection - Logical Argument
    1Reproduction results in more offspring than the size of the current population
    2 There is variationin all traits (phenotype)
    3 Much of the variation is heritable
    4There is variation in fitness as a result of having or not having certain variations of traits.
  • 13. Fitness
    Fitness: average number of offspring left by an individual relative to the number of offspring left by an average member of the population
    You could say Fitness = Relative Reproduction
    What can influence fitness?
  • 14. Natural Selection
    If natural selection occurs:
    the distribution of genotypes (phenotypes) of the next generation will reflect the distribution of the more fit members of the previous generation
    Not all traits are under the influence of natural selection
  • 15. What happens depends on the nature of the selective force: It is not progressive, it depends on the environmentWhy do some find this idea so disturbing?
  • 16. Forms of Selection
    Stabilizing selection
    Directional selection
    Disruptive selection
  • 17. Definitions
    Mutation: any change occurring in the message that a gene carries
    Provides variation upon which natural selection can act
    Usually the result of copy errors during DNA replication in mitosis or meiosis
  • 18. Definitions
    Adaptation: the condition of organisms being
    well fit for life in their environments
    as resulting from natural selection
    Non-adaptive change?
  • 19. Definitions
    Exaptation: a biological trait (adaptation) where the current biological function is different from the function of the original adaptation
    Or, you could say
    The selection pressures are now exerted on a different function than those that initially controlled the trait
  • 20.
  • 21. Definitions
    Phenotypic plasticity: sometimes the same genotype is expressed as a different phenotype in different environments
    The organism has not adapted
  • 22. Units of Evolution and Natural Selection
    Unit of evolution=Species
    can change over time based on the differential representation of genes in each generation caused by natural selection
    It is often more proper to view the population as the unit of evolution
    When are a species and population not equivalent?
  • 23. Units of Evolution and Natural Selection
    Unit of selection=An individual
    the unit that survives or does not, breeds or does not, passes on genes to the next generation or does not
    Individuals do not evolve
  • 24. How does Evolution Illustrate the History of Life?
    Phylogeny: branching diagram indicating the evolutionary history of an organism
    What does the history of life look like?
    A phylogeny is a data based hypothesis about evolutionary relationships
    How is it a hypothesis?
  • 25. Phylogeny
    What kind of information is used to make a phylogeny?
    Derived Homologies
    What are homologies?
    What does derived mean?
  • 26. Phylogeny
    Analogous: shared by 2 or more species, but not present in their common ancestor
    Likely developed by convergent evolution
    Homologous: shared by 2 or more species, also present in their common ancestor
  • 27.
  • 28. Phylogeny
    Ancestral homologies: present in common ancestor and more distant relatives
    Opposable thumb in apes
    Derived homologies: evolved in common ancestor, not present in more distant ancestors
    Opposable thumb in primates
  • 29. What types of data support evolution?
    Stephen J. Gould discusses three arguments for evolution in his essay “Evolution as Fact and Theory”
  • 30. Direct observational evidence
  • 31. Imperfections of nature
    Conflicts between selection pressures and limitations of descent
    increased brain size
    requires large pelvic outlet
    bipedal locomotion
    requires narrow pelvic outlet
  • 32. Transition fossils