Zebra Mussels (An Invasive Species)

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Zebra Mussels (An Invasive Species)
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Lamarck Review

• Important because he was one of the first to
  study how a population changes over time.
• Use and Disuse Theory if an organism wants
  something badly enough (desire), it can acquire a
  new trait by use or disuse.
• Inheritability of Acquired Traits if an
  organism acquires (gets) a trait it did not have
  before, it can then pass the trait on to its
  offspring.

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Lamarck Examples

• Giraffes
• Human Flying
• Blacksmith Muscles
• Mouse Tails
• Moths
• Finch Beaks

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Reasons Lamarck is Wrong

• Changing the phenotype does not change the
  genotype.
• Cannot pass on traits that you acquire throughout
  life must be in your DNA
• Now know more about genetics, especially
  mutations and variability in POPULATION.

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Evolution and Natural Selection
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I. Charles Darwin

• Charles Darwin is the father of evolutionary
  theory.
• What question is he trying to solve?
• Why do populations change over time?

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Darwin on HMS Beagle

• It took Darwin years to develop his theory of
  evolution eventually published ideas in book
  entitled On the Origin of Species

• He began in 1831 at age 22 when he took a job as
  a naturalist on the English ship HMS Beagle,
  which sailed around the world on a five-year
  scientific journey.

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A map of Darwins voyage
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Darwin on HMS Beagle

• As the ships naturalist, Darwin studied and
  collected biological and fossil specimens at
  every port along the route.

• After Darwin went to the Galapagos islands, the
  animals and plants he studied there helped him
  create his theory of evolution by natural
  selection.

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Evolution

• Evolution is when a POPULATION of organisms
  changes over time
• Darwin proposed the idea that evolution happens
  through natural selection.
• Developed from his idea of artificial selection
  nature provides variation and HUMANS select
  variations they find useful

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II. Natural Selection

• Natural selection is the way evolution happens.
  That is, natural selection is how organisms
  change over time.
• Natural selection is when nature selects
• organisms with good genes to live and pass on
  their genes and
• organisms with bad genes to die out

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II. Natural Selection

• In any population, there are differences between
  species.
• For example These fish are different sizes,
  shapes and speeds.
• What causes these differences?
• Mutations (alterations in DNA sequences)

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II. Natural Selection

• Organisms with helpful traits, such as being
  fast, survive better in their environment,
  compared to being slower.

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II. Natural Selection

• Over time, only the organisms with the good genes
  (in this example, fast fish) will survive and the
  new population of fish will look very different
  from their ancestors

Ancestors (Great-Grandparents)
New population of fish
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Fitness the physical traits and behaviors that
enable organisms to survive and reproduce in
their environment- Common Descent the idea
that all species have common ancestors

1. Natural SelectionSometimes called Survival of
   the Fittest

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• Darwins Theory of Natural Selection
• 1. Organisms reproduce organisms like themselves
• 2. There are variations in individuals in a given
  population these traits can be passed on.
  (caused by mutations)
• 3. Whether an individual will survive to breed
  depends upon the interaction between these
  variations the environment.
• Some variations will be favorable ? increases
  fitness
• Variations will become more common from one
  generation to the next.
• This is called natural selection (nature is
  selecting favorable traits that already exist in
  a population)
• 4. In time, natural selection will produce
  different groups of organisms (speciation)

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• What makes a variation favorable?
• One that makes it more likely for you to
• Get food
• Not get eaten
• Have children
• Thermal conservation

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Giraffes (again)!! Remember

• There is variation in traits in a population due
  to mutation (Giraffe's necks).

• More individuals are born than can survive
  called the "Struggle for Existence

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• C Giraffes with longer
• necks get better food,
• have more babies
• (greater fitness)

• C Longer necks give birth to
• longer necks
• (trait is passed on in genes)

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Results Over time, average neck length
increases
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Thus, what has happens?
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PEPPER MOTHSpre-industrialization

• Which moth would be more fit? WHY???

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PEPPER MOTHSpost-industrialization

• 01. Now, which moth would be more fit?
• WHY???
• 02. Explain how this happened as if you were
• Darwin (in terms of natural selection).

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You are Darwin. Explain why and how this change
could happen.
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Finch Beak Size

• These two finches came from the same ancestor.
• According to Darwin, how did they come to look
  different?
• What would Lamarck had said?