Natural Selection Survival of the Fittest

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Natural SelectionSurvival of the Fittest
PAST
PRESENT
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Phenotype vs. Genotype

• Natural selection acts on ________ rather than
  _________.
• Those best suited for their environment will
  ________ (taller giraffes).
• Those least suited for their environment ___
  faster and leave ________ offspring (short
  giraffes).

phenotype
PAST
PRESENT
genotype
survive
die
Tt tt tt TT
Tt tt tt tt
fewer
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Genetic variation is essential!

• _________ promote genetic variation, which helps
  ensure a species survival
• Crossing over promotes genetic variation which
  helps to ensure a species survival

Mutations
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Adaptation

• some phenotypic feature or trait that improves
  an organisms likelihood of survival and
  reproduction.
• In Georgia, there is a popular hunting area of
  forest called the Poopycack forest, where the
  Poopy Deer lives. This species of deer has 6
  ears.
• How might this adaptation have occurred and how
  is it beneficial?
• What would you expect to happen to the Poopy Deer
  population in the next 1000 years?

Q
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How does natural selection determine the
differential survival of groups of organisms?
(who is going to live?)

• Those groups of organisms who are best adapted to
  their environment will survive, while the least
  adapted will eventually die out. Some live and
  some die (differential survival).

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How does a great number of species ensure that at
least some organisms survive major changes in the
environment?

• Those who are better at adapting will survive
  major changes in the environment

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Charles Darwin

• 1st credited with theory of Evolution
• Wrote the Origin of Species
• Book based on his observations during trip

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Prezygotic and Postzygotic barriers

• Geographic isolation organisms, originally of
  same species (in same area) got separated and
  were no longer able to mate
• Reproductive Isolation organisms become
  genetically incompatible or offspring are not
  viable or offspring are not fertile.

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Geographic Isolation
Squirrel A and B live on opposite sides of the
Grand Canyon. Even though they are different
species, dont they look similar?
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Reproductive Isolation
X
mule
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Speciation

• process of new species formation, typically due
  to a favoring of certain traits.

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Speciation