Evolution is a Remodeling Process

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Evolution is a Remodeling Process
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Refinement of Existing Adaptations

• Complex structures often evolve from simpler
  structures.
• Structures do not have to be complicated to be a
  useful adaptation.

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Adaptation of Existing Structuresto New Functions

• Chitin of arthropods
• Arthropods originated in ocean and exoskeleton
  used for protection.
• As arthropods colonized land, exoskeleton adapted
  for additional function resisting water loss.
• Penguin forelimbs
• Penguins are birds and possess wings that have
  been modified into flippers.
• Penguins live in remote places (flight offers
  little advantage for escape/hunting) and food is
  more abundant in the water than land (strong
  swimming offers survival advantage).

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Evolution and Development

• Remodeling can involve changes in the rate or
  timing of some event in the development of an
  organism.
• We can investigate these control mechanisms to
  learn more about how evolution remodels certain
  features.
• Terrestrial vs. Tree Salamanders
• Tree-dwellers have shorter toes and more webbing.
• Tree-dwellers foot growth ends sooner in
  development.

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Development of Dolphin Blowhole

• In most mammals, the nose opening is located near
  the tip of the snout.
• In modern dolphins, however, it is located on the
  top of the head.
• In development, the nose opening shifts from the
  tip of the snout to its position on top of the
  head.

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What is evo-devo?

• Evolutionary developmental biology
• Some genes are more like switches than
  blueprints, because they function to initiate
  certain developmental pathways.
• The same switches can activate very different
  developmental pathways.
• Analogy power strip vs. normal plugs
• Video Explain Evo-Devo. Fast.