Unit 10 Notes

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Unit 10 Notes

• Evolution

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Evolution of Elephants
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Evolution

• Gradual change in characteristics over time
• A theory that explains how organisms change over
  a period of time
• Results in
• New organisms
• Some organisms becoming extinct

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Evolution

• Variations - differences in traits
• Adaptation - gradual changes to an organisms to
  help it survive
• Gradualism - the belief that evolutionary changes
  in organisms take several years to occur

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History of Evolution

• Spontaneous Generation is the idea that life
  could arise from nonliving matter
• In 1668, Francisco Redi developed Biogenesis
• The idea that life only comes from other life
• Disproved spontaneous generation by putting meat
  into jars

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Francisco Redi

• Redis Experiment
• Some jars were covered with a mesh cloth
• Others were left open
• Several days later maggots were on the meat in
  open jars, no maggots were on the covered meat

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Louis Pasteur

• Disproved spontaneous generation by putting broth
  in a curve neck flask and a straight neck flask
• Hypothesis was that the bacteria could not move
  up the curve neck of the flask
• Within days, the broth in the straight neck flask
  was cloudy with bacteria

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Louis Pasteur
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Jean Baptiste Lamarck

• Noticed that blacksmiths were usually muscular
• Noticed that their children would usually become
  muscular
• Hypothesized that being muscular was passed down
  from parent to offspring
• Used no scientific evidence

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Jean Baptiste Lamarck

• Use and Disuse of Organs
• Organisms constantly strive to improve themselves
  to become more advanced
• The effort to improve causes the most used body
  structure to develop and the most unused
  structure to waste away
• Principle of Acquired Traits
• The modified structure can be passed down from
  parent to offspring

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Jean Baptiste Lamarck

• Lamarck was disproved by August Weismann
• Weismann cut off tails of over a 100 mice
• mated the mice for 50 generations
• all of the mice were born with tails

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Charles Darwin

• Sailed on the Beagle as the ships naturalist
• Visited the Galapagos Islands
• Wrote the Origin of Species
• Darwins Finches

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Charles Darwin

• Darwins Theory
• All organisms compete for limited space
• Organisms produce more offspring than can survive
• Natural selection states that organisms best
  suited to the environment survive while those not
  suited may eventually die

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Charles Darwin

• Darwins Evolution
• Variation exists within a species
• Some variations are favorable
• Survival of the fittest
• The strongest will survive and reproduce
• The weak will die out
• Organisms better adapted to the environment will
  survive
• Adaptations will happen gradually
• Gradualism

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Charles Darwin
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Charles Darwin

• Natural Selection

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Charles Darwin

• Natural Selection
• Disruptive Selection
• Selection can act against the middle of a normal
  distribution after an environmental change, this
  is selection against the most common variation
  (ex. African Swallowtale Butterfly
• Directional Selection
• After several generations, the normal
  distribution shifts in the direction of change
  (ex. DDT and insects)
• Stabilizing Selection
• Environments may go through long periods of
  stability, when conditions remain about the same.
  Organisms that are best adapted to the existing
  environment will be favored, and there is
  selection against the extremes

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Rates of Evolution

• Gradualism
• Organisms evolve as a result of small adaptive
  changes
• Punctuated Equilibrium
• Short periods of rapid change in a species are
  separated by long periods of little or no change

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Speciation

• Speciation
• When one or more new organisms evolve from a
  single ancestral species
• Divergent Isolation
• When an isolated population evolves into
  different populations that cannot interbreed

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Types of Evolution

• Divergent
• Related organisms become more distant
• ex Grizzly Bears Polar Bears

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Types of Evolution

• Convergent
• Distantly related organisms develop similar
  characteristics
• ex Dolphins Penguins

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Synthesis of Organic Molecules

• Miller Urey
• Mixed water vapor, methane, ammonia, hydrogen
  gas (all inorganic) together with electrodes
  (lightning)
• After a week they produced Organic Molecules

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Prokaryotic to Eukaryotic

• Origin of an inner membrane - Cell membrane
  infolded to create compartments
• Endosymbiosis
• Mitochondria and Chloroplast (free living
  Prokaryotes) were consumed by a larger Prokaryote
• They were not digested and formed a permanent
  partnership - Symbiosis

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Human Evolution
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Evidence of Evolution

• Fossil
• Anatomical
• Embryological
• Biochemical

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Fossil Evidence

• Organisms became increasingly complex over time
• Types of fossils
• Preserved Tissue
• Preserved Trace
• Youngest fossils are on top, Oldest are on the
  bottom

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How old are fossils?

• In sedimentary rock layers, the oldest fossils
  are in the bottom layers, the youngest fossils
  are in the top layers
• Radioactive dating Carbon-14 dating

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Anatomical Evidence

• Homologous Structures
• Body parts of different organisms that have the
  same basic structure
• Example Human Arm, Bird Wing, Whale Fin, Bat
  Wing

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Anatomical Evidence

• Analogous Structures
• Body parts of different organisms that have the
  same function but different structures
• ex Birds Wing Butterflys Wing
• Vestigial Structures
• Body parts with no apparent functions
• ex human appendix, tiny hip bones in some snakes

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Embryological Evidence

• Study of early growth stages development of
  embryos
• The embryos of different organisms look very
  similar
• similar genes at work
• The DNA sequences which control early development
  remain unchanged because of little or no
  mutations

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Biochemical Evidence

• The study or the molecules that make up an
  organism
• All organisms use DNA RNA to carry information
• All living things need water energy
• All organisms synthesize proteins

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Population Genetics

• Population
• Group of organisms that live in the same are
  interbreed
• Evolution can only occur when there is a change
  in the kinds or of genes in the gene pool of a
  population (allele frequencies)

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Hardy-Weinberg Principle

• Describes the conditions that must be met in
  order for the allele frequencies to remain
  constant
• It describes genetic equilibrium
• Five conditions

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Hardy-Weinberg Principle

• 1. No Mutations
• 2. Random Mating
• 3. No Genetic Drift
• 4. No Natural Selection
• 5. No Gene Flow

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Population Genetics

• Geographic Isolation
• Organisms are separated by geographical barriers
  such as mountains or oceans
• Reproductive Isolation
• Organisms of the same species cant mate anymore
  due to the development of different mating time
• ex Frogs

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Unit 10 Notes

• Evolution