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(click for source)

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    Welcome to
    Evolution and Biodiversity

    ...a 14-week tour of

    • evolutionary theory and processes
    • the living products of organic evolution

    "Nothing in biology makes sense
    except in the light of evolution."

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    An Anonymous Survey

    Before you respond to this question, do the following:

      1. Go to Google Drive.
      2. LOG OUT of Google if you are logged into a personal account.
      3. LOG IN to your UM Google account:
      • Choose "Personal Account"
      • Select your UM email address
      • Log in with your Cane ID and password
      • You should now be able to see the embedded questions.
      4. Now go to the Bonus Quiz Portal
      5. Bookmark it for future use.

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    Belief in Evolution

    Physical evidence of evolution as a past and ongoing process is plentiful.

    Observable, natural processes can explain evolution
    without invoking the supernatural.

    And yet...


      (click on pic for more information)

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We are the products of our ancestors' choices.

Another anonymous survey, this one with three parts.

How might you explain these results?


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    Evolution Happens

    Many things evolve, from car designs to hair styles.

    • Evolution is defined as change over time.

    • Organic evolution is the descent,
      with genetic change, of living organisms
      from one generation to the next.

    But even among those who accept organic evolution
    as a naturally occuring phenomenon,
    there can be misunderstandings.

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    The Scientific Method

    Many misunderstandings about evolution originate with
    misunderstandings about science vs. non-science.

    It is extraordinarily important that we understand
    how we distinguish FACTS from BELIEFS (<-- required link!).

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    Misconceptions and Misunderstandings

    There are those who actively seek to discredit the idea of evolution
    by distorting or misrepresenting its scientific mechanisms and theories.

    But sometimes, misconceptions about evolution
    are simply a matter of misunderstanding.

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Common Misconceptions About Evolution

    Statement:

      Evolution is only a theory.

      You'll sometimes hear people say,
      "Even scientists agree that evolution is only a theory."

      True or false?

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    Statement:

      Evolutionary theory explains the origin of life on earth.

      True or false?

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    Statement:

      Evolutionary theory implies that life evolved,
      and is evolving, by chance.

      True or false?

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    Statement:

      Evolution is progress: evolving organisms are getting better.

      True or false?

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    Statement:

      Evolution has never actually been observed.

      True or false?

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    Statement:

      There are no transitional fossils ("missing links").

      True or false?

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    Statement:

      Evolution violates the Second Law of Thermodynamics.

      Entropy is defined as the energy in any closed system that is unavailable to do work.

      Entropy can be thought of as "disorder" or "chaos" in a closed system.

      The Second Law of Thermodynamics states that entropy in a closed system can never decrease.
      So the evolution of complex organisms would violate that law.

      True or false?

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We will discover and address other misconceptions and misunderstandings as we learn more.

Your assignment: Send me a question about evolution that has you wondering.



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  • THE MISCONCEPTION: Evolution is only a theory.
  • THE FACTS:

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        Hypothesis, Theory, and Law

        Science requires
        • falsifiable hypotheses and theories
        • rigorous experimental testing of hypotheses
        • observable evidence

        The word "theory" is often used colloquially
        to describe a hunch or "gut feeling" based on speculation.

        However, the scientific definitions of

        • hypothesis
        • theory
        • law
          ...are more precise.

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        Hypothesis

        A scientific hypothesis
        • is a tentative explanation for an observed phenomenon.
        • must be experimentally testable
        • cannot be proven to be true

        Example: Feather pigmentation in flamingos is influenced by carotenoids in their diet.

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        Theory

        A scientific theory
        • is a well-substantiated explanation of some aspect of the natural world
        • can be used to make predictions
        • is subject to testing, revision, and refutation

        Example: Evolution proceeds by means of natural selection. (Darwin's Theory)

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        Law

        A natural law
        • describes events in nature that occur exactly the same way,
          every time, under the same conditions
        • is dependent upon cause and effect
        • predicts a specific result under a specific set of circumstances
        • does not explain why that result occurs

        Examples: Laws of Thermodynamics

        • Energy cannot be created or destroyed, but only changed in form.
        • A closed system will to move towards a state of greater disorder/chaos.

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    • Evolution is an observable natural process (not a theory).

    • The Theory of Evolution is that earth's biodiversity arose via organic evolution.

      The "Only a Theory" argument is flawed in that it fails to separate two important things:.

        1. Species evolve from ancestral forms. (observable fact)
        2. Species evolve by means of mechanisms such as natural selection and genetic drift. (theoretical explanation)

      In other words, the only thing theoretical about evolution is how it happens.



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    • THE MISCONCEPTION: Evolution is the process by which life on earth came to be.
      THE FACTS:

        As we will learn in more detail later,
        Evolution is not the process by which life originated.

        Evolution is the process by which life has changed since its origin.

        The

        • origin of life
        • evolution of life

          ... are two very different phenomena.

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    • THE MISCONCEPTION: Evolutionary theory implies that life evolved, and is evolving, by chance.
      THE FACTS:

        Both random and non-random factors can affect evolution:

        • genetic mutations - random
        • natural selection - not random

        Changes to life on earth have been significantly driven
        by more than just random chance.

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    • THE MISCONCEPTION: Evolution is progress: evolving organisms are getting better.
    • THE FACTS:

        The idea that life evolves directionally, towards a "goal" is called orthogenesis or orthogenetic evolution
        (from the Greek ortho meaning "straight", "upright", or "correct").

        This "goal" is believed to be set by some internal mechanism or "driving force".

        As we will soon see, populations generally evolve in response to both

        • non-random factors (natural selection)
        • random factors (genetic drift)

        Random changes do not necessarily make an organism "better".

        Non-random evolutionary changes (natural selection)
        can result in organisms that are better suited to their particular environment.

        But how can one define "better" or "best"?

        As we'll see, it's all about context.

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    • THE MISCONCEPTION: Evolution has never been observed.
    • THE FACTS:

      1. Empirical data, or facts, are measurable, verifiable observations of the natural world.

      2. Patterns are characterized by

      • regularity
      • order
      • repeatability in sets of observations


      We live in an ordered universe.
      Therefore, patterns inevitably emerge among the observations.
      Most patterns are the result of some process.

      That process is described by a theory that must

      • explain all known observations
      • predict new observations

      If a single observation refutes the theory, the theory must be abandoned.


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      • THE MISCONCEPTION: There are no transitional fossils.
      • THE FACTS:

          Fossilization is RARE.
          Most living organisms decay without leaving a trace of their existence.

          Even so, there are thousands of examples of transitional fossils.
          The evolution of whales is one of the most famous examples.

          Transitional fossil records provide yet another example of pattern that supports the theory that biodiversity arose via evoltion.

          CAUTION: Fossils are NOT the most powerful line of evidence for evolution.
          Far more compelling is the homology and evidence of common ancestry in living organisms.

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      • THE MISCONCEPTION: Evolution violates the Second Law of Thermodynamics.
      • THE FACTS:

          Evolution does not violate any known laws of physics.

          This misconception is based on a misunderstanding of thermodynamics. The Second Law of Thermodynamics can be stated several ways.

          • No process is possible in which the sole result is the transfer of energy from a cooler to a hotter body.
          • The entropy of a closed system will never decrease.
          • A closed system will tend to change from an ordered to a disordered state.
          ...etc.

          The misunderstanding arises because life is not a closed system. Order arising from disorder is common in both living and non-living natural systems

          • snowflakes
          • tsunamis
          • stalactites and stalagmites
          • tide pools
          • insert your own

          Any system receiving energy (e.g., from the sun) is capable of generating order.
          The process of descent with modification via natural selection does not violate the Second Law.

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