Darwin

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Darwins Evidence of Evolution

• ADD WHATEVER IS IN YELLOW TO YOUR
  VOCABULARY/NOTES!

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Evidence

• Geographical distribution of living things
• - Similar animals living in different places
  were the product of different lines of
  evolutionary descent.

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• DNA/Proteins
• - Closely related species will have more
  similarities in their DNA and genes.

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• Homologous Structures structures that share
  common ancestry.
• Example wing, arm, and fin all have very similar
  number and organization of bones.

Analogous structures have similar function and
appearance but DO NOT share common ancestry. ex-
Dolphin fluke and Fishs fin
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• Vestigial organs/structures structures without
  function
• -They are remnants of evolutionary past.
• -Example Whales have a pelvic bone, but they
  no longer walk on land.

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• Developmental patterns
• Embryos are similar when they are developing
• It is hard to notice the difference between a
  bird embryo and a mammal embryo in the early
  stages.
• At one point, human embryos develop a coating of
  fur!

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• Fossil Record
• The fossil record provides evidence for history
  of life on earth. Paleontologists - study
  fossils.
• Fossils Traces of dead organisms such as
  footprints, insects, bones, leaf impressions,
  etc.
• Many things are now extinct (no longer living on
  earth) and fossils are the proof of their
  existence.

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Speciation Natural Selection on Physical Traits
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• Natural selection can affect the distribution of
  phenotypes (traits) and the genes that control
  them in three ways
• - Directional Selection
• - Stabilizing selection
• - Disruptive

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Directional Selection when individuals at one
end of the curve have higher fitness than
individuals in the middle or at the other end
In this case, birds with larger beaks have higher
fitness. Resulting in the average beak size
increases.
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Human babies born at an average mass are more
likely to survive than babies born either much
smaller or much larger than average.
Stabilizing Selection - when individuals near the
center of the curve have higher fitness than
individuals at either end of the curve
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Disruptive Selection individuals at the upper
and lower ends of the curve have higher fitness
than individuals near the middle.

• If average-sized seeds become scarce, a bird
  population will split into two groups one that
  eats small seeds and one that eats large seeds.

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Speciation

• Speciation - the formation of new species

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How do they separate???

• Reproductive isolation - as species evolve their
  DNA changes and eventually the two populations
  cannot interbreed and produce fertile offspring.

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Reproductive Isolation

• 3 Types -
• Behavioral Isolation
• Temporal Isolation
• Geographic Isolation

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Behavioral Isolation

• occurs when two populations have differences in
  courtship rituals and courtship behaviors that
  prevent them from interbreeding.

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Temporal Isolation

• occurs when two or more species reproduce at
  different times.

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Geographic Isolation

• occurs when populations are separated physically
  by geographic barriers including rivers,
  mountains, or other geographical features

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Patterns of Evolution
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Macroevolution

• Macroevolution refers to large-scale evolutionary
  patterns and processes that occur over long
  periods of time.

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Macroevolution

• FIVE important topics in
  macroevolution are
• extinction
• adaptive radiation
• convergent evolution
• coevolution
• punctuated equilibrium

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Extinction

• More than 99 of all species that have ever lived
  are now extinct.
• In the past, most researchers looked for a
  single, major cause for each mass extinction.
• Many paleontologists now think that mass
  extinctions were caused by several factors.

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Adaptive Radiation

• Adaptive Radiation
• the process by which a single species or a small
  group of species evolves into several different
  forms that live in different ways.
• For example, in the adaptive radiation of
  Darwin's finches, more than a dozen species
  evolved from a single species.

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Adaptive Radiation

• Adaptive radiations can occur on a much larger
  scale.
• For example, the disappearance of dinosaurs then
  resulted in the adaptive radiation of mammals.

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Adaptive Radiation

• Adaptive Radiation of Mammals

Ancestral Mammals
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Convergent Evolution

• Convergent Evolution
• The process by which unrelated organisms come to
  resemble one another
• Convergent evolution has resulted in sharks,
  dolphins, seals, and penguins.

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Coevolution

• Coevolution
• Sometimes organisms that are closely connected to
  one another by ecological interactions evolve
  together.
• The process by which two species evolve in
  response to changes in each other over time is
  called coevolution.

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Punctuated Equilibrium

• DEFINITION - a pattern of evolution in which long
  stable periods are interrupted by brief periods
  of more rapid change.

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Punctuated Equilibrium

• DISAGREEMENT!
• Darwin felt that biological change was slow and
  steady, an idea known as gradualism.