Evolution

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Evolution
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Key Points

• Heritable characteristics increase or decrease an
  organisms chance of survival
• Evolution is the change of the genetic makeup of
  a population over time
• More closely related organisms have more closely
  related DNA and proteins
• Many organisms have similar structures, and many
  organisms develop similarly

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Key Points

• Mutations that lead to evolution occur randomly
• All species on earth are related by a common
  ancestor
• The fossil record shows organisms that are no
  longer alive
• Environmental pressures, genetic drift, mutation
  and competition for resources lead to evolution

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How did life on earth begin?

• There are many theories
• Information about early earth comes from rocks
• The earth is 4.6 billion years old
• The oldest clues about life on earth are 3.5
  billion years old

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Fossils

• Fossils are preserved evidence of organisms
• 99.9 of all organisms are extinct
• Very few organisms become fossilized
• Many fossils are casts
• Minerals fill in the areas where the organism was

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Dating Methods

• Relative Dating

• A technique where items (rocks or fossils) are
  dated by comparing the soil layers
• The Law of Superposition
• Sedimentary rock is deposited in layers
• Older layers are deeper
• Newer layers are on top
• Explain the picture?

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Dating Methods

• Radiometric Dating

• Uses radioactive isotopes to date rocks or
  organic material
• Uses the half life of the isotope
• Carbon-14
• Decays to Nitrogen-14
• Half life is 5730 years
• Can date organisms up to 50,000 years
• Potassium-40
• Used to date older items
• Can only be used to date rocks
• Half life is 1.3 Billion years

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Geologic Time

• Represents major geologic events

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Spontaneous Generation-A Hypothesis

• Spontaneous generation- life arises from no life
• Francisco Redis experiment
• Redis experiment opposes the hypothesis

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Biogenesis- a theory

• Biogenesis- life arises from life
• Louis Pasteur biogenesis is true for
  microorganisms

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Origins of Life

• Simple organic molecule formation
• Organic molecules could be synthesized by simple
  reactions
• UV light from the Sun and lightning may have been
  the primary energy source

Shark Bay, Australia
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Miller and Urey

• Simple organic molecules are made from inorganic
  molecules
• Conditions were like that of early earth

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Cell Evolution

• Prokaryotes evolved first
• Archea most closely resemble earths first life
• They are autotrophs, energy does not come from
  the sun, they do not need oxygen
• Photosynthesizing prokaryotes evolved next
• Oxygen was just a byproduct
• Eukaryotes evolved by prokaryotes developing
  symbiotic relationships

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Endosymbiont Theory
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STOP

• You are a Paleontologist Activity

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Brontosaurus

• Old

New
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Natural Selection
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Darwin Natural Selection

• Darwin was a naturalist on the HMS Beagle
• He was also a companion to the captain
• He collected biological samples
• Darwin collected many birds, mockingbirds and
  finches on the Galapagos Islands
• Each island had similar birds, but they were
  slightly different

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Example of Adaptive Radiation
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Beaks specific for diet
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Artificial Selection and Natural Selection

• Humans could changes species (such as dogs) by
  artificial selection
• Darwins Hypothesis
• New species could appear gradually through small
  changes in ancestral species
• Support

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Natural Selection

• Individuals in a population show variation
• Variations are inherited
• Organisms have more offspring than can survive on
  the available resources
• Variations that increase reproductive success
  will have a greater chance of being passed on

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• Convergent evolution
• Divergent evolution

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Support for Evolution

• Fossils
• Fossils show species that lived long ago
• Ancient species share similarities with living
  species

Glyptodont
Armadillo
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Support for Evolution

• Derived traits newly evolved features that do
  not appear in common ancestors
• Feathers
• Ancestral traits
• More primitive features that do appear in
  ancestral forms

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Homologous Structures

• Anatomically similar structures inherited from a
  common ancestor
• Structures are used for different purposes

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Vestigial Structures

• Structures that are reduced in form
• They are useful in related organisms
• Features of ancestors that are no longer useful
  will become smaller or lost over time

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Analogous Structures

• Structures used for the same purpose but are not
  from a common ancestor

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Comparative Embryology

• Vertebrate embryos look very similar as embryos
• Develop differently as they get older

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More Comparative Embryology
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Comparative Biochemistry

• Common ancestry can be seen in metabolic
  molecules
• DNA
• Amino acid sequences
• More closely related organisms have similar
  sequences

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How Organisms Evolve
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Blue Skinned PeopleThe Fugate Family

• Affects an entire family from isolated Appalachia
  (Kentucky)
• Skin tinged blue ? almost purple
• Recessive diseases ? Methemoglobinemia
• Blood disorder in which an abnormal amount of
  methemoglobin -- a form of hemoglobin
• Hemoglobin - responsible for distributing oxygen
  to the body
• Family had a deficiency in the enzyme called
  cytochrome-b5 methemoglobin reductase
• blue hemoglobin never converted to red
  hemoglobin
• No side health effects
• Many Futates lived into their 80s and 90s.

Martin Fugate came to Troublesome Creek from
France in 1820 and family folklore says he was
blue. His wife carried the recessive gene. Of
their seven children, four were reported to be
blue
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Genetic Drift

• Change in allele frequency
• Caused by chance
• Seen in small populations

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• Founder Effect

• Population Bottleneck

• A small sample of a population emigrate to a new
  area
• Alleles that were uncommon in the parent
  population become popular

• The population almost goes extinct
• A few surviving members survive and reproduce

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Gene Flow
Nonrandom Mating

• Immigration and emigration
• Increases variation within a population

• Promotes inbreeding
• Can cause alleles frequency to change
• Female is usually choosey
• Male usually displays traits

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Types of Selection

• The best suited individuals survive
• Derive a situation that could cause each graph.

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Human Evolution
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Human Evolution

• What is a primate (Ape)
• Manual dexterity
• Flexible bodies
• Limber shoulders and hips
• Large Brain
• Can solve problems
• Social
• Newborns dependent on mother
• Have fewer offspring
• Are you an ape?

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Humans

• Bipedalism- changing environment
• Large Brain- evolved after bipedalism

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Primate/human Tree
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So, are we an ape?