NATURAL SELECTION EXAMPLE

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NATURAL SELECTION EXAMPLE
WHAT COLOR ARE THE ROCKS IN THE DIAGRAM? WHAT
COLOR ARE THE LIZARDS?
GRAY
GRAY
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NATURAL SELECTION EXAMPLE
WHAT COLOR LIZARDS ARE BEING TAKEN BY THE
HAWKS? WHAT TYPE OF LIZARD HAS THE ADVANTAGE FOR
THIS ENVIRONMENT?
WHITE
GRAY
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NATURAL SELECTION EXAMPLE
OVERTIME THE ROCKS BECOME COVERED WITH
SAND. WHICH LIZARD IS NOW MORE FIT TO SURVIVE?
WHITE
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FILL IN THE IDEA MAP
feed
poorly
easy
die
Do not blend in
blend
survive
well
do not feed
hard
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CHARLES DARWIN 1809-1882
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Who was Charles Darwin

• 1809- Born in Shrewsbury, England
• Wealthy family
• Father, physician Mother was daughter of James
  Wedgewood Grandfather was Eramus Darwin (famous
  philosopher).
• Raised in the countryside
• was familiar with the practice of selective
  breeding
• Indifferent Student
• Flunked out of medical school
• BA in Theology from Cambridge University by
  studying under the Reverend John Henslow (botany
  professor)
• Recommended Darwin to Captain Fitzroy for a
  survey trip around the world.

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Charles Darwin and the Journey of the Beagle

• Position as a naturalist on the HMS Beagle
• Main purpose of the trip was to survey and map
  the coast of South America
• Captain was Robert Fitz-Roy
• Darwins main purpose was to provided the
  educated captain with intellectual conversation.
  The crew members were often uneducated and not
  intellectually stimulating.

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Set sail in December of 1831
Voyage lasted 5 years.
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DARWIN QUESTIONS

• WHAT WAS DARWINS EDUCATIONAL BACKGROUND?
• WHAT WAS THE MISSION OF THE HMS BEAGLE?

-CAME FROM AN EDUCATED FAMILY (FATHER -DOCTOR
GRANDFATER-PHILOSOPHER -KNEW ABOUT SELECTIVE
BREEDING -KNEW ABOUT PLANTS FROM HIS COLLEGE
PROFESSOR
TO MAP THE COAST OF SOUTH AMERICA
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Other influences on Darwin

• Charles Lyell (Geologist)
• Wrote Principles of Geology expressed the idea
  that the earth changes over time. These
  Geological changes take millions of years to
  occur.
• Darwin read this book before leaving the
  Galapagos and began to doubt the current belief
  that the Earth was a few thousand years old.
• Lyells idea that the Earth was millions of years
  old provided the time element that Darwin needed
  to explain how adaptations could arise over time.
  

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INFLUENCES OF GEOLOGY

• 1. Who was Charles Lyell and what did he
  demonstrate?
• 2. How did Charles Lyells findings influence
  Darwin?

He was a Geologist that demonstrated that the
Earth was millions of years old.
Provided the time element needed for the
evolution of millions of species. If the Earth
could change over time then so could life.
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Influences on Darwin

• ARTIFICIAL SELECTION
• Humans have modified species over many
  generations by breeding.
• Many show little resemblance to their original
  wild ancestors.
• Examples Dogs, horses, vegetables
• Darwin reasoned that if artificial selection
  could produce new species in a short period of
  time ( a few generations) then natural selection
  could produce considerable modifications of
  species over thousands of generations.

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INFLUENCES OF ARTIFICIAL SELECTION

• 1. What is artificial selection?
• 2. In the process of artificial selection who
  determines what traits will be passed on to the
  next generation?
• 3. Can artificial selection change the physical
  and genetic qualities of a population in a short
  period of time?

Process by which humans select which traits will
be passed on to the next generation through
breeding.
HUMANS SELECT THE TRAITS
YES
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• Economist
• Rev. Thomas Malthus
• Essay on Population
• Observed that in many human populations babies
  are born faster than people die.
• Human populations are controlled by famine
  disease and war.
• Influence on Darwin--more organisms are born than
  can survive due to a limited amount of resources
  (food, water, shelter)

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INFLUENCES OF MALTHUS

• 1. Who was Thomas Malthus and what did he
  observe?
• 2. What conditions observed by Malthus control
  human populations?
• 3. How did Malthus influence Darwins thinking,
  ie. How did Darwin apply Malthuss ideas to
  animals and plants?

An Economist--observed that babies were being
born faster than people were dying.
DISEASE, WAR, FAMINE
MORE ORGANISMS ARE BORN THAN CAN SURVIVE
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Jean-Baptiste Lamarck (1744-1829).

• In charge of the invertebrate collection
• at the Natural History Museum in Paris
• Compared fossils
• Envisioned a ladder of life with the lower rungs
  occupied by simple life forms and the higher
  rungs by more complex life forms.
• Believed evolution was driven by organisms
  wanting to become more complex.
• Mechanisms for evolution included
• USE AND DISUSE- idea that organs used extensively
  would become larger and stronger and those not
  used would deteriorate/disappear.
• INHERITANCE OF ACQUIRED TRAITS-the modifications
  acquired during an organisms life could be
  inherited.

WRONG!!!!!! But he deserves credit for proposing
that evolution is the best explanation for the
fossil record and the diversity of life. Proposed
a mechanism for evolution.
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1. USE AND DISUSE--if you dont use a part of
your body it will eventually disappear.
(Wrong) 2. DESIRE FOR CHANGE--organisms could
change over time by thinking about it. 3.
ACQUIRED CHARACTERISTICS-- A trait an organism
acquires during its life could be passed on. (A
person that breaks a leg will have kids that walk
with a limp.)
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DARWIN WRITES ABOUT HIS OBSERVATIONS

• 1837- began first notebook on his theory about
  how species evolve.
• 1840- forms theory of natural selection as the
  mechanism for evolution (but does not publish
  idea)

• 1858-Darwin receives a letter from Alfred Russel
  Wallace stating the same theory of natural
  selection.
• 1859-Darwin publishes his famous book The Origin
  of Species

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The Mechanism of Evolution is Natural Selection

• 1. There is variation of traits within a species
• These traits are inheritable and are the result
  of mutations
• 2. Populations tend to produce more offspring
  than the environment can support
  (resources are limited)
• all organisms compete for limited natural
  resources
• food, water, space, mates
• 3. Those individuals with traits that are best
  adapted to the environment will produce more
  offspring (the strongest will survive) passing
  their genes onto the next generation.
• 4. Over many generations the environment selects
  the best traits and the population changes to
  become better adapted to the environment.

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HOW DID GIRAFFES ACQUIRE LONG NECKS?
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HOW WOULD LAMARCK EXPLAIN THE LONG NECKS OF
GIRAFFES?

• 1. Giraffes had ancestors with shorter necks.
• 2. Giraffes needed to reach leaves on tall trees.
• 3. In trying to get these leaves they
  stretched their necks.
• 4. When these giraffes had little giraffes
  they were born with longer necks.
• 5. After many generations all giraffes acquired
  longer necks.
• Is Lamarcks explanation correct?

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HOW WOULD DARWIN EXPLAIN THE LONG NECKS OF
GIRAFFES?

• 1. Giraffes had ancestors with shorter necks.
• 2. Some Giraffes were born with longer necks than
  average.
• 3. Those with longer necks could reach more
  leaves. They were healthier, survived better and
  produced more little giraffes than those with
  shorter necks.
• 4. After many generations, the entire giraffe
  population had long necks.

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EVOLUTION

• The process by which modern organisms descended
  from ancient organisms over time.
• Darwin descent with modification