EVOLUTION

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EVOLUTION

• -Origin of Life
• -Theory of Evolution
• -Evidence for Evolution

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• Part 1
• Theories and Origin of Life
• Take out paper and textbook
• Copy slides with

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Evolution is a Theory

• In common usage, people use the word theory to
  mean a guess. In science, does the word theory
  mean a guess?
• Name some additional theories.

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Evolution is a Theory

• Name some additional theories
• Cell Theory-cell is the basic unit of living
  things
• Quantum Theory-describes very small particles
• Germ Theory- microbes cause disease
• Plate Tectonics- continental plates are shifting
• Heliocentrism-sun is the center of the universe,
  which superseded geocentrism

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Theory of Evolution

• How has evolution risen in status to the level of
  THEORY, the same level as gravity or plate
  tectonics?
• Through repeated observations from many areas of
  life sciences.

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Where did life come from?

• First- read pages 424-428
• First Organic Molecules
• Puzzle of Lifes Origin
• Free Oxygen
• Origin of Eukaryotic Cells

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Origin of Life

• Miller-Urey Experiment

Conditions of Early Atmosphere of Earth (Before Life) Products of Experiment

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Origin of Life

• Miller-Urey Experiment

Conditions of Early Atmosphere of Earth Before Life Products of Experiment
Flask with H, methane, ammonia, H20 (no free oxygen! O2) Spark (to represent lightning) Some amino acids, and cytosine and uracil And other organic molecules
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Miller-Urey Conclusion

• What is the main idea of this experiment?
• How organic molecules (ex protein or DNA) might
  have arisen from simpler molecules

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Which scientists helped to prove biogenesis?
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What did each contribute?

• Redi
• Spallanzani
• Pasteur

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Heterotroph Hypothesis

• First cells
• Microspheres- Lipid or Protein Sphere
• like a soap bubble.
• Organic molecules were protected inside. When
  they replicated, those were the first cells.

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Building Complexity

• How might cells with organelles have first come
  about?
• What is the evidence that some cell parts arose
  in this way?

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Building Complexity

• How might cells with organelles have first come
  about?
• Endosymbiosis-one prokaryotic cell engulfed
  another, and they remained in this symbiotic
  relationship.
• What is the evidence that some cell parts arose
  in this way?
• The membranes, circular chromosomes, ribosomes
  and cell division by binary fission of
  mitochondria and chloroplasts resemble todays
  prokaryotes.

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Charles Darwin (Slide 1)

• Who is Charles Darwin?
• What was his profession?
• Where did he travel?
• What did he learn?
• What is his famous idea?

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Charles Darwin (2)

• Who is Charles Darwin? World renowned
  Naturalist-before there was Biology. Born Feb 12,
  1809, same day as Lincoln. What a day!!!
• What was his profession? Ships Naturalist
• Where did he travel? All over the world. He is
  remembered most for his observations in the
  Galapagos Islands.

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• What did he learn? That organisms change over
  long periods of time, evolution.
• What idea is he famous for? The Theory of
  Evolution by Natural Selection

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Variation among organisms

• Describe how each can vary
• Tortoises
• Saddle shaped shell for reaching higher
  vegetation or dome shaped shell if vegetation is
  more abundant. Also an intermediate form
• Bird beaks
• In finches, many varieties of beak shape to
  correspond to habitat.

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Lamarck (1)

• Describe John Baptiste-Lamarck
• Why is he such an important figure in modern
  biology?

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Lamarck (2)

• Describe John Baptiste-Lamarck
• He was a French naturalist. He published his
  hypothesis the year Darwin was born.
• He proposed the concept of Use and Disuse and
  Inheritance of Acquired Traits
• Why is he such an important figure in modern
  biology?
• Although his hypothesis hasnt been supported by
  data, his groundbreaking thoughts influenced
  future naturalists like Darwin. Plus, as we
  learned in Ghost in Your Genes, he was not
  completely wrong.

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Selection

• Discuss in your own words what is meant by
  selection.
• Give an example of natural selection.
• Give an example of artificial selection.

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Darwins Theory of Natural Selection

• 1. There is variation among organisms
• 2. More offspring are produced than can survive.
• 3. There is competition for limited resources
• 4. Natural Selection Individuals best suited for
  their environment survive and pass down their
  traits.
• 5. Descent with modification

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Race to the Finish

• Alfred Russell Wallace Was thinking of the
  very same ideas at the same time.
• When Wallace sent him an essay about his
  hypothesis, Darwin quickly published the work he
  had been accumulating for 25 years.

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Darwins Influences

• Hutton Proposed that the earth is in a constant
  state of change.
• Lyell- Proposed that these changes occur as a
  result of events such as earthquakes and
  volcanoes.
• You might remember them from Short History last
  year.

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Timeframe for evolution

• Gradualism- Evolution takes place slowly and
  consistently.
• Punctuated equilibrium- When environment changes
  suddenly- evolution occurs suddenly.
• Which would you predict would be more common with
  current global warming?

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Artificial Selection

• Give 2 examples of artificial selection
• Page 379

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Selection Ponderables

• Does selection act directly on genotypes or
  phenotypes?
• Which is more likely to be selected against,
  deleterious mutations that are dominant or those
  that are recessive? Why?
• Can selection create perfect organisms?
• Humans backs are evolved from 4-legged ancestors
  and not fully compatible w upright posture, so
  many older or very tall people have back
  problems).
• Humans have a blind spot that even the octopus
  doesnt have.
• -Blind Spot Test

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Part 2

• Evidence for Evolution

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Early Clues

• What is probably the first clue that living
  things have changed over time?
• Fossils

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Fossil Evidence

• There is a story about the history of life
  written in rock.
• Relative dating--layers of rock (index fossils)
• Absolute dating--uses radioactive isotopes
  (half-life)
• How can the age of fossils be determined?
• Carbon datingall living things made of carbon
• Carbon-14 has a half-life of 5730 years
• If a fossil has ¼ of its original C-14, how old
  is it?
• See page 445 for graph and addl problem

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Piecing the evidence together

• What other evidence has contributed to our
  current understanding?

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Geographic Distribution

• Island Patterns
• Tortoises and finches from mainland are adapted
  to fit their new island environment.
• Ex necks and shell in tortoises.
• Similar Environments
• Organisms that live in similar environments often
  come to have similar adaptations. These are
  called analogous structures.

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Darwinian Prediction

• Darwin found an orchid whose reproductive organs
  were 30 cm deep inside the flower.
• Darwin postulated that a pollinator would be
  found with a 30 cm proboscis.
• It took 40 years, guess what scientists found!...

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Darwinian Prediction

• Xanthopan morganii praedicta
• The Hawk Moth
• Guess the length of the proboscis?
• Notice its last name?
• What kind of logic?
• Inductive or deductive?

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Anatomical Evidence

• Homologous structures
• Structures that have different functions but
  arrived from same body part.
• Human arm, bird wing, turtle leg, alligator leg
  derived from an ancient, lobed fish (page 384)

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Evidence- Homologous Structures
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Anatomical Evidence

• Embryological Development
• Developing human embryo displays features from
  ancestors
• Gill pouches
• Tail
• 3 sets of kidneys in humans
• http//www.pbs.org/wgbh/nova/odyssey/clips/

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Which Embryo is Which? Click Link
http//www.exploratorium.edu/exhibits/embryo/embry
oflash.html
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Anatomical Evidence

• Did you know there are pelvic bones in snakes? In
  whales? Why?
• They are vestigial structures
• What vestigial structures do humans have?
• Appendix

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Analogous Structures

• The wing of a bird and the wing of an insect are
  not homologous. They do not arise from a common
  structure.
• They are analogous structures.
• They are two structures that have evolved
  separately to do the same job.
• Ex Birds wing insects wing
• Pouch of kangaroo pouch of oppossum

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Piecing the evidence together

• What about our new understanding of genetics? How
  does this impact our model of evolution?

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Molecular Record Evidence

• The more amino acid (or DNA base pair)
  differences, the greater the evolutionary
  distance.

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Cladogram

• Cladogram (page 384, page 660)
• Evolutionary Tree--The trunk of the tree
  represents similar traits or molecules (depending
  on how tree was made). Each branch represents a
  divergence.
• See page 452-- CLADOGRAM
• What is the common ancestor for the crab,
  barnacle and the limpit?
• Which of the above animals are most closely
  related, according to the cladogram (not the
  appearance).

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Modern Examples

• Are there any real life examples of evolution in
  modern time?
• Peppered moth story
• Bacteria superbugs (MRSA and TB)
• Human size and development
• Resistance to pesticides.
• Remember DDT?
• There are rats in England that no longer even get
  sick from 5 times the dose of pesticide that once
  killed most rats

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Industrial Melanism

• Peppered moth story
• See peppered moth sim
• See details of how the experimental method was
  implemented.
• How does this relate to the Clean Air Act?
• What types of selection can you attribute this to?

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