The History of Life

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The History of Life

• Unit V
• Chapter 17

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Extant v/s Extinct

• More than 99 percent of all species that have
  ever lived on Earth have become extinct
• The term ___________________ is used to describe
  a species that no longer has a living
  representative
• The term ___________________ is used to describe
  a species that has living representatives

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Figure 17-2 Formation of a Fossil
The Formation of Fossils
Section 17-1
Water carries small rock particles to lakes and
seas.
Dead organisms are buried by layers of sediment,
which forms new rock.
The preserved remains may later be discovered and
studied.
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4
Radioactive Dating

• __________________________ is the use of
  half-lives to determine the age of a sample
• Radioactive elements decay, or break down, into
  non-radioactive elements at a steady rate called
  a half-life
• A ___________________ is the length of time
  required for half of the radioactive atoms in a
  sample to decay
• In radioactive dating, scientists calculate the
  _________ of a sample based on the amount of
  remaining radioactive isotopes it contains

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Origin of Eukaryotic Cells

• The _________________________, championed by Lynn
  Margulis, proposes that eukaryotic cells arose
  from living communities formed by prokaryotic
  organisms

Chloroplast
Plants and plantlike protists
Aerobic bacteria
Ancient Prokaryotes
Photosynthetic bacteria
Nuclear envelope evolving
Mitochondrion
Primitive Photosynthetic Eukaryote
Animals, fungi, and non-plantlike protists
Ancient Anaerobic Prokaryote
Primitive Aerobic Eukaryote
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6
Patterns of Evolution

• ______________________ refers to the large scale
  evolutionary changes that take place over long
  periods of time
• Six important patterns of macroevolution are
• ______________________
• ______________________
• ______________________
• ______________________
• ______________________
• ______________________

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Mass Extinctions

• Extinctions occur all the time
• More than ________ of all species that ever lived
  are extinct today
• Usually, extinctions occur at a _________________
  rate
• Several times, however, huge numbers of species
  have disappeared in mass extinctions
• Paleontologists think that most mass extinctions
  in the past were caused by multiple factors
• Asteroids
• Volcanic activity
• Changing position of continents
• Changing sea levels

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Adaptive Radiation

• The evolution of many diversely adapted species
  from a common ancestor upon introduction to
  various new environmental opportunities and
  challenges is called _____________________________
  ____.
• Adaptive radiation typically occurs when a few
  organisms make their way to new, often distant
  areas or when environmental changes cause
  numerous extinctions, opening up ecological
  niches for the survivors.
• Fossil evidence indicates that mammals underwent
  a dramatic adaptive radiation after the mass
  extinctions of dinosaurs 65 mya.

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Convergent Evolution

• __________________ describes 2 unrelated species
  that share similar traits.
• These similarities are not due to common
  ancestry, but rather a result of similar
  _____________________ factors.

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Coevolution

• __________________ describes the evolution of one
  species in response to new adaptations that
  appear in another species of which the first
  shares close interaction

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Punctuated Equilibrium

• _______________________ is a pattern of evolution
  in which long stable periods (gradualism) are
  interrupted by brief periods of more rapid change
• Typically occurs when new niches become available
  following a ________________________

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Developmental Genes Body Plans

• _____________________ are a stretch of DNA
  sequence found in genes involved in the
  regulation of the development (morphogenesis) of
  animals, fungi and plants
• Correlations between Hox genes and major
  evolutionary events are apparentmajor changes
  between animal phyla are correlated with
  duplications in Hox genes or an increase in the
  number of Hox genes

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Speciation Flow Chart
Section 17-4
Species
that are
in
under
under
form
in
in
can undergo
can undergo
can undergo
can undergo
can undergo
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