Chapter 15 Evolution: Evidence and Theory

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Chapter 15 Evolution Evidence and Theory

• The Fossil Record
• Theories of Evolution
• Evolution in Process

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Section 15-1 The Fossil Record

• Fossil evidence shows a long history of life on
  Earth. The fossil record shows that forms of
  organisms appeared, lasted for long periods of
  time, and then disappeared, only to be followed
  by newer forms of life that also eventually
  disappeared. The history of life is one of
  constant change and a tremendous diversity of
  life-forms

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Nature of Fossils

• A fossil is a trace of long-dead organisms.
• Fossils are often found in layers of sedimentary
  rock, which is formed when sediment, such as
  dust, sand, or mud is deposited by wind and
  water.
• Usually develop from the hard body parts which
  are replaced by minerals over time

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Nature of Fossils

• Mold is essentially an imprint in rock in the
  shape of an organism.
• Some molds eventually are filled with hard
  minerals, forming a cast, a rock-like model of
  the organism

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Nature of Fossils

• Robert Hooke (1635-1703) published his conclusion
  that fossils are the remains of plants and
  animals. He hypothesized that living organisms
  had somehow been turned to rock

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Distribution of Fossils

• Nicolaus Steno (1638-1686) made an important
  contribution toward a modern understanding of
  Earths geological and biological history.
• In 1669, he proposed the law of superposition,
  which states that successive layers of rock or
  soil were deposited on top of one another by wind
  or water

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Distribution of Fossils
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Distribution of Fossils

• The lowest stratum, or layer, in a cross section
  of Earth is oldest, while the top stratum is the
  most recent.
• Fossils found within a single stratum are of the
  same approximate age.
• Relative age of a fossil says that a given fossil
  is younger or older than another based on what
  stratum it is found
• Absolute age could be estimated from radioactive
  dating

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Distribution of Fossils

• The fossil record indicates that there were
  several mass extinctions, brief periods during
  which large numbers of species disappeared.
• Mass extinctions probably resulted from drastic
  changes in the environment, perhaps following
  periods of volcanic activity or collisions with
  asteroids.

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Distribution of Fossils

• Biogeography is the study of the geological
  distribution of fossils and of living organisms.
• A comparison of recently formed fossil types with
  types of living organisms in the same geographic
  area shows that new organisms arise in areas
  where similar forms already lived.

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Natural Selection15-2

• A Critical Thinking Approach

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Start Thinking???(Write answers in your notes)

• Define Evolution in your own words
• How do you think evolution happens? (What is the
  mechanism)
• How long do you think evolution takes???

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Problem Solving

• Cheetahs are the worlds fastest land mammal.
  They have the ability to run almost 70 mph in
  pursuit of prey. All other big cats can only run
  about 35 mph over very short distances
• Do you think the cheetahs speed is important to
  its survival? Why or why not?
• How do you think a biologist would explain the
  cheetahs speed, based on the fact that their
  ancestors (and all other cats) only run 35 mph)
• Remember, you are trying to think of a way that
  all cheetahs got faster over time

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Georges Cuvier (1769-1832)
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Georges Cuvier

• Saw org. as complete wholes, w/ each body part
  fully integrated into the entire org. No single
  part could be altered w/o damaging the entire
  org.
• Also suggested appearance of new org. in fossil
  record occurred through special creation events
  following natural catastrophes

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Questions

• How do you think Cuvier would explain the
  cheetahs speed?
• Do you think Cuviers explanation is scientific?
  Why or why not?
• How could test Cuviers ideas
• Same as it ever was

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Jean-Baptiste Lamarck (1744-1829)
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Jean-Baptiste Lamarck-part 1

• 3 basic ideas
• A change in the envir causes a resulting change
  in the org. behavior
• The behavior change causes the org. to use or not
  use various organs
• The added use of an organ will cause it to grow
  become more complex, the disuse of an organ will
  cause it to atrophy or waste away
• For Example, Lamarck thought that giraffes got
  longer necks by stretching to reach food. By
  using all of the muscles in the neck, their necks
  got longer. The giraffes would then pass on the
  extra height to their offspring, who would be
  born just as tall as their parents.
• Use it or lose it

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Questions

• Do you think Lamarcks explanation is scientific?
  Why or why not?
• How could you test Lamarcks ideas?
• How do you think Lamarck would explain the
  cheetahs speed?
• How could you test the ideas about inheritance?

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Doberman Tail Docking?Body Builders?War
Amputees?
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John Stackable or the Governator?
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Charles Darwin

• 4 Basic Ideas
• There are variations w/in populations of org.
• Variations can be passed to offspring
• Each generation produces more offspring than
  survive to adulthood
• The org. w/ the favorable characteristics survive
  better and reproduce more often, thus
  transmitting their traits to the next generation

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Charles Darwin 1809-1882
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Questions

• How do you think Charles Darwin explained the
  cheetahs speed?
• Do you think Charles Darwins explanation is
  scientific? Why or why not?
• How could you test Charles Darwins ideas?
• NATURAL SELECTION

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Reflection

• Cheetahs are the worlds fastest land mammal.
  They have the ability to run almost 70 mph in
  pursuit of prey. All other big cats can only run
  about 35 mph over very short distances
• Review your answer to this question How do you
  think a biologist would explain the cheetahs
  speed, based on the fact that their ancestors
  (and all other cats) only run 35 mph?
• Which of the 3 evolutionary thinkers does your
  explanation sound like???

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Classwork
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Who Said This???

• The fennics ears grew large b/c the heat of the
  desert caused the fenic to use its ears to
  release heat. The ears grew b/c of this new
  added use.
• After its ears grew it passed the trait for
  bigger ears onto its offspring, which also used
  their ears more which caused more growth over
  time the fennics ears became what we see today.

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Who said this???

• The viper became wonderfully camouflaged b/c each
  generation of vipers has variations in their
  camouflage.
• The vipers w/ the best camo are more likely to
  escape becoming dinner for some predator. Also
  the vipers w/ the best camo are more likely to
  get more food b/c they were better able to sneak
  up on their prey.
• Meanwhile the poorly camod vipers are more
  likely to be eaten to suffer from lack of food.
• The result is that the better camod vipers
  survive better and reproduce more often than
  their poorly camod counterparts.
• Each generation of vipers receives its genes from
  the survivors of previous generations, so the
  collection of genes is being filtered, in a
  sense, w/ the genes for poor camo being removed
  genes for good camo being maintained.

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Who said this???

• Feathered feet are an advantage for a bird in a
  cold climate.
• In the past the snowy owl pop. Had lots of
  variation in the amount of feathers on their
  feet, but in each generation the owls w/ the most
  feathers on their feet ( therefore the best
  insulated feet) had the best chance of surviving
  the cold enetually reproducing.
• The owls w/ less insulated feet would have
  difficulty in surviving the cold and consequently
  reproduced less than other owls.
• Over many generations of owls, the characteristic
  of highly feathered feet became prominent

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15-3 Evidence of Evolution

• Homologous Structures similar features
  originated in shared ancestor.
• i.e. beaks of birds, forelimbs (fig. 15-7)
• Analogous Strucures same function look alike,
  but different structures.
• i.e. (fig. 15-8) Hummingbird humming moth
• Vestigial Structures Useful to ancestors but
  not to modern organism.
• i.e. Whales evolved from land animals (hind legs

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Homologous Structures
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Analogous Structures
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Vestigial Structures
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Patterns of Evolution

• Coevolution change of 2 or more species in
  close association w/ each other.
• i.e. bats flowers (fig. 15-10)
• Convergent Evolution Look similar, but not
  related at all.
• i.e. Shark porpoise
• Divergent Evolution 2 or more related
  populations or species become more more
  dissimilar ( Can result in new species)
• i.e. Galapagos Finches, dogs (fig. 15-11)

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