chapter 1 evobio

• Evolution is:

  • Change in inheritable traits and behavior in a population over generations
  • Changes in species over long periods of time
  • Change in traits caused by changes in genes (in DNA) that code for those traits
  • All life on Earth shares a common ancestor
• What evolution is not:

  1. Evolution is not about things getting "better and better" or more complex

  • Selection is about survival and reproduction
  • Organisms with traits that help them survive long enough to reproduce will pass their genes on

  2. Evolution is not about organisms "trying" to adapt

  • "Trying" does not change genes, only inheritable traits already in a population can be passed on

  3. Evolution does not give organisms what they "need"

  • Individuals with traits that help them survive environmental change may pass those traits on while others die
• 4. Evolution does not mean individuals in a population slowly change

  • Change happens to populations over generations as those with unfavorable traits are weeded out and those with favorable traits are more likely to reproduce

  5. Evolution is not a theory of how life began

  • Evolution explains how living organisms change over generations
• Early ideas of evolution:

  • Aristotle viewed the living world as fixed and unchanging, with humans on top of a ladder of inferior to superior species
  • George Louis LeClerk, Compte de Buffon sought naturalistic explanations for fossils and proposed the theory of organic change based on logic rather than evidence
  • James Hutton and Charles Lyell proposed Uniformitarianism, stating that physical laws shaping the Earth have always done so
  • Jean-Baptiste de Lamarck used the theory of Inheritance of Acquired Characteristics to explain change in organisms
• Charles Darwin and Alfred Russell Wallace devised a model for organic change based on observations of living and fossil organisms

  • Natural Selection was the first evidence-based mechanism for evolution proposed
  • Selection happens each generation, favoring individuals with traits that help them survive and reproduce
  • Over generations, individuals with favorable traits increase while those with unfavorable traits decrease
• Evidence for evolution:

  • Fossils show species that existed in the past that no longer exist today
  • Homologous Structures suggest a shared set of genes arising from common ancestry
  • Vestigial Structures like hip bones in whales and ear-wiggling muscles in humans
  • Analogous Structures show similar body forms in less related species living in similar environments
  • Embryological Similarities demonstrate shared genes between groups of organisms
  • Biochemical and Genetic Analysis show shared genes for many traits between related species
• • Natural Selection favors organisms best adapted to the environment
• EVOLUTION CONTRADICTS THE BIBLE

  EVOLUTION IS A SCIENTIFIC THEORY

  ➢ Theories are evidence-supported explanations

  for natural phenomenon.

  ➢ To exist, theories must have abundant evidence

  from many well-tested hypotheses.

  ➢ Theories grow from evidence. Theorizing

  without evidence is not a science.
• ristotle (384-222 BC) viewed the living world

  as fixed and unchanging. All living things could

  be arranged in a ladder from inferior to superior,

  with humans on top. Aristotle’s views influenced

  thought for over 200 years.
• eorge Louis LeClerk, Compte de Buffon (1707-

  1788) sought naturalistic explanation for fossils.

  Buffon devised one of the first theories of

  organic change. However, Buffon’s ideas were

  grounded in logic rather that in evidence from

  the natural world, as much as science was at the

  time.

  o Buffon suggested that organisms had

  a basic form, the “internal mold,”

  which could be shaped by the

  environment.

  o Buffon thought the “internal mold”

  was caused by particles in an

  organism while it was an embryo. All

  animals he said, had a basic form:

  horse-like, dog-like, cat-like, and so

  on.
• ames Hutton (1726-1797)/ Charles Lyell (1797-

  1875) These two naturalists are best known for

  the theory of Uniformitarianism, proposed by

  Hutton and expanded by Lyell.

  Uniformitarianism states that the physical laws

  that now shape the earth have always done so,

  and that the past can be understood by studying

  the present. Both suggested that the Erath is very

  old.
• Georges Cuvier (1769-1832) was a student of Buffon
• Cuvier disagreed with Buffon about organic change
• Cuvier was an anatomist who pointed out that animals had features that helped them survive
• If these features changed, it could be harmful
• Cuvier studied fossils and identified several new animals based on fossils
• Cuvier had his own explanation for fossils
• Cuvier doubted Uniformitarianism and used Catastrophism to explain the fossils of the Paris basin
• He proposed one natural origin of life, followed by unpredictable catastrophes beyond known physical laws
• After each catastrophe, organisms from other places moved in
• Georges Cuvier (1769-1832) was a student of Buffon but disagreed about organic change
• Cuvier was an anatomist who pointed out that animals had features that helped them survive
• Cuvier studied fossils and identified several new animals based on fossils
• Cuvier doubted Uniformitarianism and used Catastrophism to explain the fossils of the Paris basin
• He proposed one natural origin of life, followed by unpredictable catastrophes beyond known physical laws
• After each catastrophe, organisms from other places moved in
• Jean-Baptiste de Lamarck (1744 - 1829) was also

  a student of Buffon. Like Buffon, Lamarck

  sought a naturalistic explanation for the

  diversity of modern organisms and the animals

  seen in the fossil record.

  o Lamarck used the theory of

  Inheritance of Acquired

  Characteristics, a widely heldbelief at

  the time, to explain change in

  organisms. Blacksmiths, for example,

  were thought to pass their well￾developed right arms on to their sons.
• amarck’s Organic Theory of Development

  o Organisms are shaped by their

  environment.

  o Change is goal-directed -- organisms

  have an internal drive to become

  more and more complex.

  o Use and disuse of parts causes change

  that is passed on from generation to

  generation.
• Charles Darwin (1809-1882) and Alfred Russell Wallace (1823-1913) devised a model for organic change based on observations of living and fossil organisms
• Natural Selection was the first evidence-based mechanism for evolution proposed by Darwin and Wallace
• Darwin and Wallace observed that change does not happen equally to all members of a population, contrary to Buffon and Lamarck's beliefs
• Selection happens each generation according to Darwin and Wallace
• Some individuals have traits that help them survive and reproduce, while others have traits that put them at a disadvantage
• Over generations, the number of

  individuals with favorable traits

  increases while those with

  unfavorable traits decrease
• EVIDENCE FOR EVOLUTION

  • Both Darwin and Wallace were convinced that

  evolution -- change in the traits of a population

  over time -- did happen.

  • Darwin spent over 20 years collecting evidence

  and reading research by others before he wrote

  On the Origin of Species. He found many

  features of organisms that suggested they were

  related by ancestry.
• Fossils- showed that species existed in the past

  that no longer exist today, and species exist

  today that did not exist in the past.
• yell

  ✓ Natural forces produce layers of rock

  ✓ Slow repeated process

  ✓ Uniformitarianism

  ✓ The Earth is very old
• Smith

  ✓ Rocks found in layers

  ✓ Fossils in layers are consistent

  ✓ Law of superposition
• Lyell

  ✓ Natural forces produce layers of rock

  ✓ Slow repeated process

  ✓ Uniformitarianism

  ✓ The Earth is very old

  ✓

  Slow natural geologic processes

  • Dating of rocks by elemental analysis
• In many groups of organisms, fossils

  demonstrated change from one form to another

  over long periods of time.